diff --git a/wp-admin/includes/class-custom-background.php b/wp-admin/includes/class-custom-background.php
index fa89e10e42..07a72dd1b1 100644
--- a/wp-admin/includes/class-custom-background.php
+++ b/wp-admin/includes/class-custom-background.php
@@ -11,6 +11,7 @@
  *
  * @since 3.0.0
  */
+#[AllowDynamicProperties]
 class Custom_Background {
 
 	/**
diff --git a/wp-admin/includes/class-custom-image-header.php b/wp-admin/includes/class-custom-image-header.php
index e59cd16284..c8809ade2f 100644
--- a/wp-admin/includes/class-custom-image-header.php
+++ b/wp-admin/includes/class-custom-image-header.php
@@ -11,6 +11,7 @@
  *
  * @since 2.1.0
  */
+#[AllowDynamicProperties]
 class Custom_Image_Header {
 
 	/**
diff --git a/wp-admin/includes/class-file-upload-upgrader.php b/wp-admin/includes/class-file-upload-upgrader.php
index 28cc4402c7..d7c459dd60 100644
--- a/wp-admin/includes/class-file-upload-upgrader.php
+++ b/wp-admin/includes/class-file-upload-upgrader.php
@@ -16,6 +16,7 @@
  * @since 2.8.0
  * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  */
+#[AllowDynamicProperties]
 class File_Upload_Upgrader {
 
 	/**
diff --git a/wp-admin/includes/class-wp-automatic-updater.php b/wp-admin/includes/class-wp-automatic-updater.php
index c8227c3fc3..e453539deb 100644
--- a/wp-admin/includes/class-wp-automatic-updater.php
+++ b/wp-admin/includes/class-wp-automatic-updater.php
@@ -13,6 +13,7 @@
  * @since 3.7.0
  * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  */
+#[AllowDynamicProperties]
 class WP_Automatic_Updater {
 
 	/**
diff --git a/wp-admin/includes/class-wp-community-events.php b/wp-admin/includes/class-wp-community-events.php
index 3f43f8d1db..1a09bec848 100644
--- a/wp-admin/includes/class-wp-community-events.php
+++ b/wp-admin/includes/class-wp-community-events.php
@@ -14,6 +14,7 @@
  *
  * @since 4.8.0
  */
+#[AllowDynamicProperties]
 class WP_Community_Events {
 	/**
 	 * ID for a WordPress user account.
diff --git a/wp-admin/includes/class-wp-debug-data.php b/wp-admin/includes/class-wp-debug-data.php
index a921fc4dcb..ab0926d3ac 100644
--- a/wp-admin/includes/class-wp-debug-data.php
+++ b/wp-admin/includes/class-wp-debug-data.php
@@ -7,6 +7,7 @@
  * @since 5.2.0
  */
 
+#[AllowDynamicProperties]
 class WP_Debug_Data {
 	/**
 	 * Calls all core functions to check for updates.
diff --git a/wp-admin/includes/class-wp-filesystem-base.php b/wp-admin/includes/class-wp-filesystem-base.php
index 8d83b24dd6..aae09e8dfa 100644
--- a/wp-admin/includes/class-wp-filesystem-base.php
+++ b/wp-admin/includes/class-wp-filesystem-base.php
@@ -11,6 +11,7 @@
  *
  * @since 2.5.0
  */
+#[AllowDynamicProperties]
 class WP_Filesystem_Base {
 
 	/**
diff --git a/wp-admin/includes/class-wp-importer.php b/wp-admin/includes/class-wp-importer.php
index 4c6d518f97..4804c888b2 100644
--- a/wp-admin/includes/class-wp-importer.php
+++ b/wp-admin/includes/class-wp-importer.php
@@ -2,6 +2,7 @@
 /**
  * WP_Importer base class
  */
+#[AllowDynamicProperties]
 class WP_Importer {
 	/**
 	 * Class Constructor
diff --git a/wp-admin/includes/class-wp-internal-pointers.php b/wp-admin/includes/class-wp-internal-pointers.php
index 08cf817744..884f27ea1f 100644
--- a/wp-admin/includes/class-wp-internal-pointers.php
+++ b/wp-admin/includes/class-wp-internal-pointers.php
@@ -12,6 +12,7 @@
  *
  * @since 3.3.0
  */
+#[AllowDynamicProperties]
 final class WP_Internal_Pointers {
 	/**
 	 * Initializes the new feature pointers.
diff --git a/wp-admin/includes/class-wp-list-table.php b/wp-admin/includes/class-wp-list-table.php
index 599c69d2ad..046e9515d8 100644
--- a/wp-admin/includes/class-wp-list-table.php
+++ b/wp-admin/includes/class-wp-list-table.php
@@ -13,6 +13,7 @@
  * @since 3.1.0
  * @access private
  */
+#[AllowDynamicProperties]
 class WP_List_Table {
 
 	/**
diff --git a/wp-admin/includes/class-wp-privacy-policy-content.php b/wp-admin/includes/class-wp-privacy-policy-content.php
index bbc46c0a70..9b11d09a66 100644
--- a/wp-admin/includes/class-wp-privacy-policy-content.php
+++ b/wp-admin/includes/class-wp-privacy-policy-content.php
@@ -7,6 +7,7 @@
  * @since 4.9.6
  */
 
+#[AllowDynamicProperties]
 final class WP_Privacy_Policy_Content {
 
 	private static $policy_content = array();
diff --git a/wp-admin/includes/class-wp-screen.php b/wp-admin/includes/class-wp-screen.php
index 7caf17beb5..7b7290011c 100644
--- a/wp-admin/includes/class-wp-screen.php
+++ b/wp-admin/includes/class-wp-screen.php
@@ -12,6 +12,7 @@
  *
  * @since 3.3.0
  */
+#[AllowDynamicProperties]
 final class WP_Screen {
 	/**
 	 * Any action associated with the screen.
diff --git a/wp-admin/includes/class-wp-site-health-auto-updates.php b/wp-admin/includes/class-wp-site-health-auto-updates.php
index 5393b6f3c9..4880d02302 100644
--- a/wp-admin/includes/class-wp-site-health-auto-updates.php
+++ b/wp-admin/includes/class-wp-site-health-auto-updates.php
@@ -7,6 +7,7 @@
  * @since 5.2.0
  */
 
+#[AllowDynamicProperties]
 class WP_Site_Health_Auto_Updates {
 	/**
 	 * WP_Site_Health_Auto_Updates constructor.
diff --git a/wp-admin/includes/class-wp-site-health.php b/wp-admin/includes/class-wp-site-health.php
index 7c94e8be10..3c717cc659 100644
--- a/wp-admin/includes/class-wp-site-health.php
+++ b/wp-admin/includes/class-wp-site-health.php
@@ -7,6 +7,7 @@
  * @since 5.2.0
  */
 
+#[AllowDynamicProperties]
 class WP_Site_Health {
 	private static $instance = null;
 
diff --git a/wp-admin/includes/class-wp-site-icon.php b/wp-admin/includes/class-wp-site-icon.php
index d153b6f826..e799c7fb79 100644
--- a/wp-admin/includes/class-wp-site-icon.php
+++ b/wp-admin/includes/class-wp-site-icon.php
@@ -12,6 +12,7 @@
  *
  * @since 4.3.0
  */
+#[AllowDynamicProperties]
 class WP_Site_Icon {
 
 	/**
diff --git a/wp-admin/includes/class-wp-upgrader-skin.php b/wp-admin/includes/class-wp-upgrader-skin.php
index bb7e7bbf3b..d0d2a39b01 100644
--- a/wp-admin/includes/class-wp-upgrader-skin.php
+++ b/wp-admin/includes/class-wp-upgrader-skin.php
@@ -13,6 +13,7 @@
  * @since 2.8.0
  * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
+#[AllowDynamicProperties]
 class WP_Upgrader_Skin {
 
 	/**
diff --git a/wp-admin/includes/class-wp-upgrader.php b/wp-admin/includes/class-wp-upgrader.php
index 412b383abe..a2b2c9ed06 100644
--- a/wp-admin/includes/class-wp-upgrader.php
+++ b/wp-admin/includes/class-wp-upgrader.php
@@ -48,6 +48,7 @@ require_once ABSPATH . 'wp-admin/includes/class-wp-ajax-upgrader-skin.php';
  *
  * @since 2.8.0
  */
+#[AllowDynamicProperties]
 class WP_Upgrader {
 
 	/**
diff --git a/wp-includes/class-wp-admin-bar.php b/wp-includes/class-wp-admin-bar.php
index 6eab9c3fdb..406d76459b 100644
--- a/wp-includes/class-wp-admin-bar.php
+++ b/wp-includes/class-wp-admin-bar.php
@@ -12,6 +12,7 @@
  *
  * @since 3.1.0
  */
+#[AllowDynamicProperties]
 class WP_Admin_Bar {
 	private $nodes = array();
 	private $bound = false;
diff --git a/wp-includes/class-wp-ajax-response.php b/wp-includes/class-wp-ajax-response.php
index e4024102a8..fb90d2ddac 100644
--- a/wp-includes/class-wp-ajax-response.php
+++ b/wp-includes/class-wp-ajax-response.php
@@ -5,6 +5,7 @@
  * @package WordPress
  * @since 2.1.0
  */
+#[AllowDynamicProperties]
 class WP_Ajax_Response {
 	/**
 	 * Store XML responses to send.
diff --git a/wp-includes/class-wp-application-passwords.php b/wp-includes/class-wp-application-passwords.php
index c41f8ad372..c4e34350fc 100644
--- a/wp-includes/class-wp-application-passwords.php
+++ b/wp-includes/class-wp-application-passwords.php
@@ -11,6 +11,7 @@
  *
  * @package WordPress
  */
+#[AllowDynamicProperties]
 class WP_Application_Passwords {
 
 	/**
diff --git a/wp-includes/class-wp-block-editor-context.php b/wp-includes/class-wp-block-editor-context.php
index fd594bcad0..bb2d44e5a1 100644
--- a/wp-includes/class-wp-block-editor-context.php
+++ b/wp-includes/class-wp-block-editor-context.php
@@ -11,6 +11,7 @@
  *
  * @since 5.8.0
  */
+#[AllowDynamicProperties]
 final class WP_Block_Editor_Context {
 	/**
 	 * String that identifies the block editor being rendered. Can be one of:
diff --git a/wp-includes/class-wp-block-list.php b/wp-includes/class-wp-block-list.php
index 2b0750bfee..9b7caaf01f 100644
--- a/wp-includes/class-wp-block-list.php
+++ b/wp-includes/class-wp-block-list.php
@@ -11,6 +11,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 class WP_Block_List implements Iterator, ArrayAccess, Countable {
 
 	/**
diff --git a/wp-includes/class-wp-block-pattern-categories-registry.php b/wp-includes/class-wp-block-pattern-categories-registry.php
index f4d881c4e2..3d37a5940a 100644
--- a/wp-includes/class-wp-block-pattern-categories-registry.php
+++ b/wp-includes/class-wp-block-pattern-categories-registry.php
@@ -10,6 +10,7 @@
 /**
  * Class used for interacting with block pattern categories.
  */
+#[AllowDynamicProperties]
 final class WP_Block_Pattern_Categories_Registry {
 	/**
 	 * Registered block pattern categories array.
diff --git a/wp-includes/class-wp-block-patterns-registry.php b/wp-includes/class-wp-block-patterns-registry.php
index 8b312d56c2..bfbc651341 100644
--- a/wp-includes/class-wp-block-patterns-registry.php
+++ b/wp-includes/class-wp-block-patterns-registry.php
@@ -12,6 +12,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 final class WP_Block_Patterns_Registry {
 	/**
 	 * Registered block patterns array.
diff --git a/wp-includes/class-wp-block-styles-registry.php b/wp-includes/class-wp-block-styles-registry.php
index b9a59f6d6e..317c6489b2 100644
--- a/wp-includes/class-wp-block-styles-registry.php
+++ b/wp-includes/class-wp-block-styles-registry.php
@@ -12,6 +12,7 @@
  *
  * @since 5.3.0
  */
+#[AllowDynamicProperties]
 final class WP_Block_Styles_Registry {
 	/**
 	 * Registered block styles, as `$block_name => $block_style_name => $block_style_properties` multidimensional arrays.
diff --git a/wp-includes/class-wp-block-supports.php b/wp-includes/class-wp-block-supports.php
index 703d03a629..a8e2ecb36b 100644
--- a/wp-includes/class-wp-block-supports.php
+++ b/wp-includes/class-wp-block-supports.php
@@ -14,6 +14,7 @@
  *
  * @access private
  */
+#[AllowDynamicProperties]
 class WP_Block_Supports {
 
 	/**
diff --git a/wp-includes/class-wp-block-template.php b/wp-includes/class-wp-block-template.php
index 51dbdbfbc3..898ddf0dd3 100644
--- a/wp-includes/class-wp-block-template.php
+++ b/wp-includes/class-wp-block-template.php
@@ -11,6 +11,7 @@
  *
  * @since 5.8.0
  */
+#[AllowDynamicProperties]
 class WP_Block_Template {
 
 	/**
diff --git a/wp-includes/class-wp-block-type-registry.php b/wp-includes/class-wp-block-type-registry.php
index c9a5776c55..84adecd5d0 100644
--- a/wp-includes/class-wp-block-type-registry.php
+++ b/wp-includes/class-wp-block-type-registry.php
@@ -12,6 +12,7 @@
  *
  * @since 5.0.0
  */
+#[AllowDynamicProperties]
 final class WP_Block_Type_Registry {
 	/**
 	 * Registered block types, as `$name => $instance` pairs.
diff --git a/wp-includes/class-wp-block-type.php b/wp-includes/class-wp-block-type.php
index 1c01120f87..10ad3e0422 100644
--- a/wp-includes/class-wp-block-type.php
+++ b/wp-includes/class-wp-block-type.php
@@ -14,6 +14,7 @@
  *
  * @see register_block_type()
  */
+#[AllowDynamicProperties]
 class WP_Block_Type {
 
 	/**
diff --git a/wp-includes/class-wp-block.php b/wp-includes/class-wp-block.php
index 33c0e6a355..9be22081c3 100644
--- a/wp-includes/class-wp-block.php
+++ b/wp-includes/class-wp-block.php
@@ -12,6 +12,7 @@
  * @since 5.5.0
  * @property array $attributes
  */
+#[AllowDynamicProperties]
 class WP_Block {
 
 	/**
diff --git a/wp-includes/class-wp-comment-query.php b/wp-includes/class-wp-comment-query.php
index 5b0ce51dab..dad512c419 100644
--- a/wp-includes/class-wp-comment-query.php
+++ b/wp-includes/class-wp-comment-query.php
@@ -14,6 +14,7 @@
  *
  * @see WP_Comment_Query::__construct() for accepted arguments.
  */
+#[AllowDynamicProperties]
 class WP_Comment_Query {
 
 	/**
diff --git a/wp-includes/class-wp-comment.php b/wp-includes/class-wp-comment.php
index 864065b7ec..c5f8cc49f4 100644
--- a/wp-includes/class-wp-comment.php
+++ b/wp-includes/class-wp-comment.php
@@ -12,6 +12,7 @@
  *
  * @since 4.4.0
  */
+#[AllowDynamicProperties]
 final class WP_Comment {
 
 	/**
diff --git a/wp-includes/class-wp-customize-control.php b/wp-includes/class-wp-customize-control.php
index 63cc5f65ae..64ed528cc2 100644
--- a/wp-includes/class-wp-customize-control.php
+++ b/wp-includes/class-wp-customize-control.php
@@ -12,6 +12,7 @@
  *
  * @since 3.4.0
  */
+#[AllowDynamicProperties]
 class WP_Customize_Control {
 
 	/**
diff --git a/wp-includes/class-wp-customize-manager.php b/wp-includes/class-wp-customize-manager.php
index 3b3259c573..e53a6ec477 100644
--- a/wp-includes/class-wp-customize-manager.php
+++ b/wp-includes/class-wp-customize-manager.php
@@ -20,6 +20,7 @@
  *
  * @since 3.4.0
  */
+#[AllowDynamicProperties]
 final class WP_Customize_Manager {
 	/**
 	 * An instance of the theme being previewed.
diff --git a/wp-includes/class-wp-customize-nav-menus.php b/wp-includes/class-wp-customize-nav-menus.php
index 341a7f572a..d34fc59b97 100644
--- a/wp-includes/class-wp-customize-nav-menus.php
+++ b/wp-includes/class-wp-customize-nav-menus.php
@@ -16,6 +16,7 @@
  *
  * @see WP_Customize_Manager
  */
+#[AllowDynamicProperties]
 final class WP_Customize_Nav_Menus {
 
 	/**
diff --git a/wp-includes/class-wp-customize-panel.php b/wp-includes/class-wp-customize-panel.php
index 88d72f83fc..14ec8aad46 100644
--- a/wp-includes/class-wp-customize-panel.php
+++ b/wp-includes/class-wp-customize-panel.php
@@ -16,6 +16,7 @@
  *
  * @see WP_Customize_Manager
  */
+#[AllowDynamicProperties]
 class WP_Customize_Panel {
 
 	/**
diff --git a/wp-includes/class-wp-customize-section.php b/wp-includes/class-wp-customize-section.php
index 97da8a9e35..87b176c301 100644
--- a/wp-includes/class-wp-customize-section.php
+++ b/wp-includes/class-wp-customize-section.php
@@ -16,6 +16,7 @@
  *
  * @see WP_Customize_Manager
  */
+#[AllowDynamicProperties]
 class WP_Customize_Section {
 
 	/**
diff --git a/wp-includes/class-wp-customize-setting.php b/wp-includes/class-wp-customize-setting.php
index e7a1030c76..33b9436f85 100644
--- a/wp-includes/class-wp-customize-setting.php
+++ b/wp-includes/class-wp-customize-setting.php
@@ -17,6 +17,7 @@
  * @see WP_Customize_Manager
  * @link https://developer.wordpress.org/themes/customize-api
  */
+#[AllowDynamicProperties]
 class WP_Customize_Setting {
 	/**
 	 * Customizer bootstrap instance.
diff --git a/wp-includes/class-wp-customize-widgets.php b/wp-includes/class-wp-customize-widgets.php
index 9b4a0fa1c5..2bf8a39a25 100644
--- a/wp-includes/class-wp-customize-widgets.php
+++ b/wp-includes/class-wp-customize-widgets.php
@@ -16,6 +16,7 @@
  *
  * @see WP_Customize_Manager
  */
+#[AllowDynamicProperties]
 final class WP_Customize_Widgets {
 
 	/**
diff --git a/wp-includes/class-wp-date-query.php b/wp-includes/class-wp-date-query.php
index 1fa3652176..faa657dde5 100644
--- a/wp-includes/class-wp-date-query.php
+++ b/wp-includes/class-wp-date-query.php
@@ -14,6 +14,7 @@
  *
  * @since 3.7.0
  */
+#[AllowDynamicProperties]
 class WP_Date_Query {
 	/**
 	 * Array of date queries.
diff --git a/wp-includes/class-wp-dependency.php b/wp-includes/class-wp-dependency.php
index ad4cd11caa..c4335b9bab 100644
--- a/wp-includes/class-wp-dependency.php
+++ b/wp-includes/class-wp-dependency.php
@@ -16,6 +16,7 @@
  * @access private
  * @since 2.6.0
  */
+#[AllowDynamicProperties]
 class _WP_Dependency {
 	/**
 	 * The handle name.
diff --git a/wp-includes/class-wp-editor.php b/wp-includes/class-wp-editor.php
index 9a772d909c..41f379a838 100644
--- a/wp-includes/class-wp-editor.php
+++ b/wp-includes/class-wp-editor.php
@@ -8,6 +8,7 @@
  * Private, not included by default. See wp_editor() in wp-includes/general-template.php.
  */
 
+#[AllowDynamicProperties]
 final class _WP_Editors {
 	public static $mce_locale;
 
diff --git a/wp-includes/class-wp-embed.php b/wp-includes/class-wp-embed.php
index 677a5944c4..8ce3483228 100644
--- a/wp-includes/class-wp-embed.php
+++ b/wp-includes/class-wp-embed.php
@@ -6,6 +6,7 @@
  * @subpackage Embed
  * @since 2.9.0
  */
+#[AllowDynamicProperties]
 class WP_Embed {
 	public $handlers = array();
 	public $post_ID;
diff --git a/wp-includes/class-wp-error.php b/wp-includes/class-wp-error.php
index d34c70a2e9..c8a976fb14 100644
--- a/wp-includes/class-wp-error.php
+++ b/wp-includes/class-wp-error.php
@@ -15,6 +15,7 @@
  *
  * @since 2.1.0
  */
+#[AllowDynamicProperties]
 class WP_Error {
 	/**
 	 * Stores the list of errors.
diff --git a/wp-includes/class-wp-fatal-error-handler.php b/wp-includes/class-wp-fatal-error-handler.php
index 1fc5e0b968..55d328fbab 100644
--- a/wp-includes/class-wp-fatal-error-handler.php
+++ b/wp-includes/class-wp-fatal-error-handler.php
@@ -16,6 +16,7 @@
  *
  * @since 5.2.0
  */
+#[AllowDynamicProperties]
 class WP_Fatal_Error_Handler {
 
 	/**
diff --git a/wp-includes/class-wp-feed-cache-transient.php b/wp-includes/class-wp-feed-cache-transient.php
index f304ef8a6e..1d39932af4 100644
--- a/wp-includes/class-wp-feed-cache-transient.php
+++ b/wp-includes/class-wp-feed-cache-transient.php
@@ -12,6 +12,7 @@
  *
  * @since 2.8.0
  */
+#[AllowDynamicProperties]
 class WP_Feed_Cache_Transient {
 
 	/**
diff --git a/wp-includes/class-wp-feed-cache.php b/wp-includes/class-wp-feed-cache.php
index b3d03ab422..d86b0fb7db 100644
--- a/wp-includes/class-wp-feed-cache.php
+++ b/wp-includes/class-wp-feed-cache.php
@@ -22,6 +22,7 @@ _deprecated_file(
  *
  * @see SimplePie_Cache
  */
+#[AllowDynamicProperties]
 class WP_Feed_Cache extends SimplePie_Cache {
 
 	/**
diff --git a/wp-includes/class-wp-hook.php b/wp-includes/class-wp-hook.php
index 018db1c967..4796503dcc 100644
--- a/wp-includes/class-wp-hook.php
+++ b/wp-includes/class-wp-hook.php
@@ -15,6 +15,7 @@
  * @see Iterator
  * @see ArrayAccess
  */
+#[AllowDynamicProperties]
 final class WP_Hook implements Iterator, ArrayAccess {
 
 	/**
diff --git a/wp-includes/class-wp-http-cookie.php b/wp-includes/class-wp-http-cookie.php
index 5fa2de7644..7f5a64d023 100644
--- a/wp-includes/class-wp-http-cookie.php
+++ b/wp-includes/class-wp-http-cookie.php
@@ -18,6 +18,7 @@
  *
  * @since 2.8.0
  */
+#[AllowDynamicProperties]
 class WP_Http_Cookie {
 
 	/**
diff --git a/wp-includes/class-wp-http-curl.php b/wp-includes/class-wp-http-curl.php
index 0e389c4563..9b201af110 100644
--- a/wp-includes/class-wp-http-curl.php
+++ b/wp-includes/class-wp-http-curl.php
@@ -16,6 +16,7 @@
  *
  * @since 2.7.0
  */
+#[AllowDynamicProperties]
 class WP_Http_Curl {
 
 	/**
diff --git a/wp-includes/class-wp-http-encoding.php b/wp-includes/class-wp-http-encoding.php
index e9e94e4d77..255b2114ea 100644
--- a/wp-includes/class-wp-http-encoding.php
+++ b/wp-includes/class-wp-http-encoding.php
@@ -14,6 +14,7 @@
  *
  * @since 2.8.0
  */
+#[AllowDynamicProperties]
 class WP_Http_Encoding {
 
 	/**
diff --git a/wp-includes/class-wp-http-ixr-client.php b/wp-includes/class-wp-http-ixr-client.php
index fef16e831d..d45ca150eb 100644
--- a/wp-includes/class-wp-http-ixr-client.php
+++ b/wp-includes/class-wp-http-ixr-client.php
@@ -5,6 +5,7 @@
  * @package WordPress
  * @since 3.1.0
  */
+#[AllowDynamicProperties]
 class WP_HTTP_IXR_Client extends IXR_Client {
 	public $scheme;
 	/**
diff --git a/wp-includes/class-wp-http-proxy.php b/wp-includes/class-wp-http-proxy.php
index 4408b9ba26..3e3d1f684e 100644
--- a/wp-includes/class-wp-http-proxy.php
+++ b/wp-includes/class-wp-http-proxy.php
@@ -39,6 +39,7 @@
  *
  * @since 2.8.0
  */
+#[AllowDynamicProperties]
 class WP_HTTP_Proxy {
 
 	/**
diff --git a/wp-includes/class-wp-http-requests-hooks.php b/wp-includes/class-wp-http-requests-hooks.php
index c54fdc0b8f..dac64dd6eb 100644
--- a/wp-includes/class-wp-http-requests-hooks.php
+++ b/wp-includes/class-wp-http-requests-hooks.php
@@ -14,6 +14,7 @@
  *
  * @see Requests_Hooks
  */
+#[AllowDynamicProperties]
 class WP_HTTP_Requests_Hooks extends Requests_Hooks {
 	/**
 	 * Requested URL.
diff --git a/wp-includes/class-wp-http-response.php b/wp-includes/class-wp-http-response.php
index ae28d8954b..d102877885 100644
--- a/wp-includes/class-wp-http-response.php
+++ b/wp-includes/class-wp-http-response.php
@@ -12,6 +12,7 @@
  *
  * @since 4.4.0
  */
+#[AllowDynamicProperties]
 class WP_HTTP_Response {
 
 	/**
diff --git a/wp-includes/class-wp-http-streams.php b/wp-includes/class-wp-http-streams.php
index a5d0694da3..48078cfafa 100644
--- a/wp-includes/class-wp-http-streams.php
+++ b/wp-includes/class-wp-http-streams.php
@@ -13,6 +13,7 @@
  * @since 2.7.0
  * @since 3.7.0 Combined with the fsockopen transport and switched to `stream_socket_client()`.
  */
+#[AllowDynamicProperties]
 class WP_Http_Streams {
 	/**
 	 * Send a HTTP request to a URI using PHP Streams.
diff --git a/wp-includes/class-wp-http.php b/wp-includes/class-wp-http.php
index 73be956f4d..e96713e718 100644
--- a/wp-includes/class-wp-http.php
+++ b/wp-includes/class-wp-http.php
@@ -25,6 +25,7 @@ if ( ! class_exists( 'Requests' ) ) {
  *
  * @since 2.7.0
  */
+#[AllowDynamicProperties]
 class WP_Http {
 
 	// Aliases for HTTP response codes.
diff --git a/wp-includes/class-wp-image-editor.php b/wp-includes/class-wp-image-editor.php
index db94fc7dfe..67d1bda83f 100644
--- a/wp-includes/class-wp-image-editor.php
+++ b/wp-includes/class-wp-image-editor.php
@@ -11,6 +11,7 @@
  *
  * @since 3.5.0
  */
+#[AllowDynamicProperties]
 abstract class WP_Image_Editor {
 	protected $file              = null;
 	protected $size              = null;
diff --git a/wp-includes/class-wp-list-util.php b/wp-includes/class-wp-list-util.php
index 49fd3a00af..a2ccfb5412 100644
--- a/wp-includes/class-wp-list-util.php
+++ b/wp-includes/class-wp-list-util.php
@@ -13,6 +13,7 @@
  *
  * @since 4.7.0
  */
+#[AllowDynamicProperties]
 class WP_List_Util {
 	/**
 	 * The input array.
diff --git a/wp-includes/class-wp-locale-switcher.php b/wp-includes/class-wp-locale-switcher.php
index 3cbd613a43..028ad48d55 100644
--- a/wp-includes/class-wp-locale-switcher.php
+++ b/wp-includes/class-wp-locale-switcher.php
@@ -12,6 +12,7 @@
  *
  * @since 4.7.0
  */
+#[AllowDynamicProperties]
 class WP_Locale_Switcher {
 	/**
 	 * Locale stack.
diff --git a/wp-includes/class-wp-locale.php b/wp-includes/class-wp-locale.php
index 962fc9f2ca..ca98f9d301 100644
--- a/wp-includes/class-wp-locale.php
+++ b/wp-includes/class-wp-locale.php
@@ -13,6 +13,7 @@
  * @since 2.1.0
  * @since 4.6.0 Moved to its own file from wp-includes/locale.php.
  */
+#[AllowDynamicProperties]
 class WP_Locale {
 	/**
 	 * Stores the translated strings for the full weekday names.
diff --git a/wp-includes/class-wp-matchesmapregex.php b/wp-includes/class-wp-matchesmapregex.php
index cdb39077e2..558bd98667 100644
--- a/wp-includes/class-wp-matchesmapregex.php
+++ b/wp-includes/class-wp-matchesmapregex.php
@@ -11,6 +11,7 @@
  *
  * @since 2.9.0
  */
+#[AllowDynamicProperties]
 class WP_MatchesMapRegex {
 	/**
 	 * store for matches
diff --git a/wp-includes/class-wp-meta-query.php b/wp-includes/class-wp-meta-query.php
index f66b2fac5f..41b5f02f08 100644
--- a/wp-includes/class-wp-meta-query.php
+++ b/wp-includes/class-wp-meta-query.php
@@ -19,6 +19,7 @@
  *
  * @since 3.2.0
  */
+#[AllowDynamicProperties]
 class WP_Meta_Query {
 	/**
 	 * Array of metadata queries.
diff --git a/wp-includes/class-wp-metadata-lazyloader.php b/wp-includes/class-wp-metadata-lazyloader.php
index 67eacc99ae..4a03633de0 100644
--- a/wp-includes/class-wp-metadata-lazyloader.php
+++ b/wp-includes/class-wp-metadata-lazyloader.php
@@ -28,6 +28,7 @@
  *
  * @since 4.5.0
  */
+#[AllowDynamicProperties]
 class WP_Metadata_Lazyloader {
 	/**
 	 * Pending objects queue.
diff --git a/wp-includes/class-wp-network-query.php b/wp-includes/class-wp-network-query.php
index 269b960303..4f8a2a3a2e 100644
--- a/wp-includes/class-wp-network-query.php
+++ b/wp-includes/class-wp-network-query.php
@@ -14,6 +14,7 @@
  *
  * @see WP_Network_Query::__construct() for accepted arguments.
  */
+#[AllowDynamicProperties]
 class WP_Network_Query {
 
 	/**
diff --git a/wp-includes/class-wp-network.php b/wp-includes/class-wp-network.php
index f9dfad0957..75b407e541 100644
--- a/wp-includes/class-wp-network.php
+++ b/wp-includes/class-wp-network.php
@@ -21,6 +21,7 @@
  * @property int $id
  * @property int $site_id
  */
+#[AllowDynamicProperties]
 class WP_Network {
 
 	/**
diff --git a/wp-includes/class-wp-object-cache.php b/wp-includes/class-wp-object-cache.php
index c22fd6298d..6ca91a34fd 100644
--- a/wp-includes/class-wp-object-cache.php
+++ b/wp-includes/class-wp-object-cache.php
@@ -21,6 +21,7 @@
  *
  * @since 2.0.0
  */
+#[AllowDynamicProperties]
 class WP_Object_Cache {
 
 	/**
diff --git a/wp-includes/class-wp-oembed-controller.php b/wp-includes/class-wp-oembed-controller.php
index 046c5c0a3a..22fceb54a9 100644
--- a/wp-includes/class-wp-oembed-controller.php
+++ b/wp-includes/class-wp-oembed-controller.php
@@ -15,6 +15,7 @@
  *
  * @since 4.4.0
  */
+#[AllowDynamicProperties]
 final class WP_oEmbed_Controller {
 	/**
 	 * Register the oEmbed REST API route.
diff --git a/wp-includes/class-wp-oembed.php b/wp-includes/class-wp-oembed.php
index 58f5e484c4..ea666c1442 100644
--- a/wp-includes/class-wp-oembed.php
+++ b/wp-includes/class-wp-oembed.php
@@ -16,6 +16,7 @@
  *
  * @since 2.9.0
  */
+#[AllowDynamicProperties]
 class WP_oEmbed {
 
 	/**
diff --git a/wp-includes/class-wp-paused-extensions-storage.php b/wp-includes/class-wp-paused-extensions-storage.php
index a2859d308f..4658277289 100644
--- a/wp-includes/class-wp-paused-extensions-storage.php
+++ b/wp-includes/class-wp-paused-extensions-storage.php
@@ -11,6 +11,7 @@
  *
  * @since 5.2.0
  */
+#[AllowDynamicProperties]
 class WP_Paused_Extensions_Storage {
 
 	/**
diff --git a/wp-includes/class-wp-post-type.php b/wp-includes/class-wp-post-type.php
index 3c3ec0e3ab..ab9fccc681 100644
--- a/wp-includes/class-wp-post-type.php
+++ b/wp-includes/class-wp-post-type.php
@@ -14,6 +14,7 @@
  *
  * @see register_post_type()
  */
+#[AllowDynamicProperties]
 final class WP_Post_Type {
 	/**
 	 * Post type key.
diff --git a/wp-includes/class-wp-post.php b/wp-includes/class-wp-post.php
index fe059d00aa..682b000f39 100644
--- a/wp-includes/class-wp-post.php
+++ b/wp-includes/class-wp-post.php
@@ -18,6 +18,7 @@
  * @property-read int[]    $post_category
  * @property-read string[] $tags_input
  */
+#[AllowDynamicProperties]
 final class WP_Post {
 
 	/**
diff --git a/wp-includes/class-wp-query.php b/wp-includes/class-wp-query.php
index 32b5fafaf3..4b17618907 100644
--- a/wp-includes/class-wp-query.php
+++ b/wp-includes/class-wp-query.php
@@ -15,6 +15,7 @@
  * @since 1.5.0
  * @since 4.5.0 Removed the `$comments_popup` property.
  */
+#[AllowDynamicProperties]
 class WP_Query {
 
 	/**
diff --git a/wp-includes/class-wp-recovery-mode-cookie-service.php b/wp-includes/class-wp-recovery-mode-cookie-service.php
index 47329d6c64..df59b35780 100644
--- a/wp-includes/class-wp-recovery-mode-cookie-service.php
+++ b/wp-includes/class-wp-recovery-mode-cookie-service.php
@@ -11,6 +11,7 @@
  *
  * @since 5.2.0
  */
+#[AllowDynamicProperties]
 final class WP_Recovery_Mode_Cookie_Service {
 
 	/**
diff --git a/wp-includes/class-wp-recovery-mode-email-service.php b/wp-includes/class-wp-recovery-mode-email-service.php
index e375f38bf1..013901f90e 100644
--- a/wp-includes/class-wp-recovery-mode-email-service.php
+++ b/wp-includes/class-wp-recovery-mode-email-service.php
@@ -11,6 +11,7 @@
  *
  * @since 5.2.0
  */
+#[AllowDynamicProperties]
 final class WP_Recovery_Mode_Email_Service {
 
 	const RATE_LIMIT_OPTION = 'recovery_mode_email_last_sent';
diff --git a/wp-includes/class-wp-recovery-mode-key-service.php b/wp-includes/class-wp-recovery-mode-key-service.php
index 6e533d04a9..5ab0f8c3f9 100644
--- a/wp-includes/class-wp-recovery-mode-key-service.php
+++ b/wp-includes/class-wp-recovery-mode-key-service.php
@@ -11,6 +11,7 @@
  *
  * @since 5.2.0
  */
+#[AllowDynamicProperties]
 final class WP_Recovery_Mode_Key_Service {
 
 	/**
diff --git a/wp-includes/class-wp-recovery-mode-link-service.php b/wp-includes/class-wp-recovery-mode-link-service.php
index 1b4b96373a..4fb888c5d6 100644
--- a/wp-includes/class-wp-recovery-mode-link-service.php
+++ b/wp-includes/class-wp-recovery-mode-link-service.php
@@ -11,6 +11,7 @@
  *
  * @since 5.2.0
  */
+#[AllowDynamicProperties]
 class WP_Recovery_Mode_Link_Service {
 	const LOGIN_ACTION_ENTER   = 'enter_recovery_mode';
 	const LOGIN_ACTION_ENTERED = 'entered_recovery_mode';
diff --git a/wp-includes/class-wp-recovery-mode.php b/wp-includes/class-wp-recovery-mode.php
index e61290090e..b30eb408e3 100644
--- a/wp-includes/class-wp-recovery-mode.php
+++ b/wp-includes/class-wp-recovery-mode.php
@@ -11,6 +11,7 @@
  *
  * @since 5.2.0
  */
+#[AllowDynamicProperties]
 class WP_Recovery_Mode {
 
 	const EXIT_ACTION = 'exit_recovery_mode';
diff --git a/wp-includes/class-wp-rewrite.php b/wp-includes/class-wp-rewrite.php
index a1a262aa7b..a20de7128e 100644
--- a/wp-includes/class-wp-rewrite.php
+++ b/wp-includes/class-wp-rewrite.php
@@ -22,6 +22,7 @@
  *
  * @since 1.5.0
  */
+#[AllowDynamicProperties]
 class WP_Rewrite {
 	/**
 	 * Permalink structure for posts.
diff --git a/wp-includes/class-wp-role.php b/wp-includes/class-wp-role.php
index 33f484ac97..6f25c3cb03 100644
--- a/wp-includes/class-wp-role.php
+++ b/wp-includes/class-wp-role.php
@@ -12,6 +12,7 @@
  *
  * @since 2.0.0
  */
+#[AllowDynamicProperties]
 class WP_Role {
 	/**
 	 * Role name.
diff --git a/wp-includes/class-wp-roles.php b/wp-includes/class-wp-roles.php
index 23d5d76723..f224250fa2 100644
--- a/wp-includes/class-wp-roles.php
+++ b/wp-includes/class-wp-roles.php
@@ -23,6 +23,7 @@
  *
  * @since 2.0.0
  */
+#[AllowDynamicProperties]
 class WP_Roles {
 	/**
 	 * List of roles and capabilities.
diff --git a/wp-includes/class-wp-session-tokens.php b/wp-includes/class-wp-session-tokens.php
index a1a779b236..feabf698b7 100644
--- a/wp-includes/class-wp-session-tokens.php
+++ b/wp-includes/class-wp-session-tokens.php
@@ -12,6 +12,7 @@
  *
  * @since 4.0.0
  */
+#[AllowDynamicProperties]
 abstract class WP_Session_Tokens {
 
 	/**
diff --git a/wp-includes/class-wp-simplepie-file.php b/wp-includes/class-wp-simplepie-file.php
index 83cc324863..a0125aaf1d 100644
--- a/wp-includes/class-wp-simplepie-file.php
+++ b/wp-includes/class-wp-simplepie-file.php
@@ -17,6 +17,7 @@
  *
  * @see SimplePie_File
  */
+#[AllowDynamicProperties]
 class WP_SimplePie_File extends SimplePie_File {
 
 	/**
diff --git a/wp-includes/class-wp-simplepie-sanitize-kses.php b/wp-includes/class-wp-simplepie-sanitize-kses.php
index 183fe07ca7..4e7602cda4 100644
--- a/wp-includes/class-wp-simplepie-sanitize-kses.php
+++ b/wp-includes/class-wp-simplepie-sanitize-kses.php
@@ -17,6 +17,7 @@
  *
  * @see SimplePie_Sanitize
  */
+#[AllowDynamicProperties]
 class WP_SimplePie_Sanitize_KSES extends SimplePie_Sanitize {
 
 	/**
diff --git a/wp-includes/class-wp-site-query.php b/wp-includes/class-wp-site-query.php
index b620713989..a90cc9de8d 100644
--- a/wp-includes/class-wp-site-query.php
+++ b/wp-includes/class-wp-site-query.php
@@ -14,6 +14,7 @@
  *
  * @see WP_Site_Query::__construct() for accepted arguments.
  */
+#[AllowDynamicProperties]
 class WP_Site_Query {
 
 	/**
diff --git a/wp-includes/class-wp-site.php b/wp-includes/class-wp-site.php
index 1e253ec636..fcd07cd5e3 100644
--- a/wp-includes/class-wp-site.php
+++ b/wp-includes/class-wp-site.php
@@ -22,6 +22,7 @@
  * @property int    $post_count
  * @property string $home
  */
+#[AllowDynamicProperties]
 final class WP_Site {
 
 	/**
diff --git a/wp-includes/class-wp-tax-query.php b/wp-includes/class-wp-tax-query.php
index 9f4aeaaa76..e7b1e2a95a 100644
--- a/wp-includes/class-wp-tax-query.php
+++ b/wp-includes/class-wp-tax-query.php
@@ -19,6 +19,7 @@
  *
  * @since 3.1.0
  */
+#[AllowDynamicProperties]
 class WP_Tax_Query {
 
 	/**
diff --git a/wp-includes/class-wp-taxonomy.php b/wp-includes/class-wp-taxonomy.php
index 0fac7a0501..1f7eed96f6 100644
--- a/wp-includes/class-wp-taxonomy.php
+++ b/wp-includes/class-wp-taxonomy.php
@@ -12,6 +12,7 @@
  *
  * @since 4.7.0
  */
+#[AllowDynamicProperties]
 final class WP_Taxonomy {
 	/**
 	 * Taxonomy key.
diff --git a/wp-includes/class-wp-term-query.php b/wp-includes/class-wp-term-query.php
index 5c430c8459..18c85e89b2 100644
--- a/wp-includes/class-wp-term-query.php
+++ b/wp-includes/class-wp-term-query.php
@@ -15,6 +15,7 @@
  *
  * @see WP_Term_Query::__construct() for accepted arguments.
  */
+#[AllowDynamicProperties]
 class WP_Term_Query {
 
 	/**
diff --git a/wp-includes/class-wp-term.php b/wp-includes/class-wp-term.php
index f79ab8633b..0f5631353e 100644
--- a/wp-includes/class-wp-term.php
+++ b/wp-includes/class-wp-term.php
@@ -14,6 +14,7 @@
  *
  * @property-read object $data Sanitized term data.
  */
+#[AllowDynamicProperties]
 final class WP_Term {
 
 	/**
diff --git a/wp-includes/class-wp-text-diff-renderer-inline.php b/wp-includes/class-wp-text-diff-renderer-inline.php
index 62a33033e3..eaba1b61ed 100644
--- a/wp-includes/class-wp-text-diff-renderer-inline.php
+++ b/wp-includes/class-wp-text-diff-renderer-inline.php
@@ -13,6 +13,7 @@
  * @since 2.6.0
  * @uses Text_Diff_Renderer_inline Extends
  */
+#[AllowDynamicProperties]
 class WP_Text_Diff_Renderer_inline extends Text_Diff_Renderer_inline {
 
 	/**
diff --git a/wp-includes/class-wp-text-diff-renderer-table.php b/wp-includes/class-wp-text-diff-renderer-table.php
index 43c0d0e422..a74b8019f4 100644
--- a/wp-includes/class-wp-text-diff-renderer-table.php
+++ b/wp-includes/class-wp-text-diff-renderer-table.php
@@ -13,6 +13,7 @@
  * @since 2.6.0
  * @uses Text_Diff_Renderer Extends
  */
+#[AllowDynamicProperties]
 class WP_Text_Diff_Renderer_Table extends Text_Diff_Renderer {
 
 	/**
diff --git a/wp-includes/class-wp-textdomain-registry.php b/wp-includes/class-wp-textdomain-registry.php
index d4d8968ac9..403fff9813 100644
--- a/wp-includes/class-wp-textdomain-registry.php
+++ b/wp-includes/class-wp-textdomain-registry.php
@@ -12,6 +12,7 @@
  *
  * @since 6.1.0
  */
+#[AllowDynamicProperties]
 class WP_Textdomain_Registry {
 	/**
 	 * List of domains and all their language directory paths for each locale.
diff --git a/wp-includes/class-wp-theme-json-resolver.php b/wp-includes/class-wp-theme-json-resolver.php
index c9bb42cac5..cf5ffa2e2b 100644
--- a/wp-includes/class-wp-theme-json-resolver.php
+++ b/wp-includes/class-wp-theme-json-resolver.php
@@ -17,6 +17,7 @@
  *
  * @access private
  */
+#[AllowDynamicProperties]
 class WP_Theme_JSON_Resolver {
 
 	/**
diff --git a/wp-includes/class-wp-theme-json-schema.php b/wp-includes/class-wp-theme-json-schema.php
index 462af76376..2e35a12c2b 100644
--- a/wp-includes/class-wp-theme-json-schema.php
+++ b/wp-includes/class-wp-theme-json-schema.php
@@ -17,6 +17,7 @@
  * @since 5.9.0
  * @access private
  */
+#[AllowDynamicProperties]
 class WP_Theme_JSON_Schema {
 
 	/**
diff --git a/wp-includes/class-wp-theme-json.php b/wp-includes/class-wp-theme-json.php
index 69a349f970..e5eb5a7391 100644
--- a/wp-includes/class-wp-theme-json.php
+++ b/wp-includes/class-wp-theme-json.php
@@ -16,6 +16,7 @@
  *
  * @access private
  */
+#[AllowDynamicProperties]
 class WP_Theme_JSON {
 
 	/**
diff --git a/wp-includes/class-wp-theme.php b/wp-includes/class-wp-theme.php
index 55a9359a13..84e7d1f571 100644
--- a/wp-includes/class-wp-theme.php
+++ b/wp-includes/class-wp-theme.php
@@ -6,6 +6,7 @@
  * @subpackage Theme
  * @since 3.4.0
  */
+#[AllowDynamicProperties]
 final class WP_Theme implements ArrayAccess {
 
 	/**
diff --git a/wp-includes/class-wp-user-query.php b/wp-includes/class-wp-user-query.php
index f894027e67..330882494e 100644
--- a/wp-includes/class-wp-user-query.php
+++ b/wp-includes/class-wp-user-query.php
@@ -14,6 +14,7 @@
  *
  * @see WP_User_Query::prepare_query() for information on accepted arguments.
  */
+#[AllowDynamicProperties]
 class WP_User_Query {
 
 	/**
diff --git a/wp-includes/class-wp-user-request.php b/wp-includes/class-wp-user-request.php
index 7e445cfa63..8c66dcdf81 100644
--- a/wp-includes/class-wp-user-request.php
+++ b/wp-includes/class-wp-user-request.php
@@ -6,6 +6,7 @@
  *
  * @since 4.9.6
  */
+#[AllowDynamicProperties]
 final class WP_User_Request {
 	/**
 	 * Request ID.
diff --git a/wp-includes/class-wp-user.php b/wp-includes/class-wp-user.php
index 45878986f7..b190960009 100644
--- a/wp-includes/class-wp-user.php
+++ b/wp-includes/class-wp-user.php
@@ -36,6 +36,7 @@
  * @property string $syntax_highlighting
  * @property string $use_ssl
  */
+#[AllowDynamicProperties]
 class WP_User {
 	/**
 	 * User data container.
diff --git a/wp-includes/class-wp-walker.php b/wp-includes/class-wp-walker.php
index d47d25261f..f7f4715ed1 100644
--- a/wp-includes/class-wp-walker.php
+++ b/wp-includes/class-wp-walker.php
@@ -11,6 +11,7 @@
  * @package WordPress
  * @abstract
  */
+#[AllowDynamicProperties]
 class Walker {
 	/**
 	 * What the class handles.
diff --git a/wp-includes/class-wp-widget-factory.php b/wp-includes/class-wp-widget-factory.php
index a7554846a2..ed719b9d4d 100644
--- a/wp-includes/class-wp-widget-factory.php
+++ b/wp-includes/class-wp-widget-factory.php
@@ -13,6 +13,7 @@
  * @since 2.8.0
  * @since 4.4.0 Moved to its own file from wp-includes/widgets.php
  */
+#[AllowDynamicProperties]
 class WP_Widget_Factory {
 
 	/**
diff --git a/wp-includes/class-wp-widget.php b/wp-includes/class-wp-widget.php
index 086e9e9ffb..79a1efe1bf 100644
--- a/wp-includes/class-wp-widget.php
+++ b/wp-includes/class-wp-widget.php
@@ -17,6 +17,7 @@
  * @since 2.8.0
  * @since 4.4.0 Moved to its own file from wp-includes/widgets.php
  */
+#[AllowDynamicProperties]
 class WP_Widget {
 
 	/**
diff --git a/wp-includes/class-wp-xmlrpc-server.php b/wp-includes/class-wp-xmlrpc-server.php
index f48f4a01f5..6e3ee0a13a 100644
--- a/wp-includes/class-wp-xmlrpc-server.php
+++ b/wp-includes/class-wp-xmlrpc-server.php
@@ -20,6 +20,7 @@
  *
  * @see IXR_Server
  */
+#[AllowDynamicProperties]
 class wp_xmlrpc_server extends IXR_Server {
 	/**
 	 * Methods.
diff --git a/wp-includes/class-wp.php b/wp-includes/class-wp.php
index ca9399e4e5..8d67820545 100644
--- a/wp-includes/class-wp.php
+++ b/wp-includes/class-wp.php
@@ -5,6 +5,7 @@
  * @package WordPress
  * @since 2.0.0
  */
+#[AllowDynamicProperties]
 class WP {
 	/**
 	 * Public query variables.
diff --git a/wp-includes/class-wpdb.php b/wp-includes/class-wpdb.php
index 81a43900f5..e81b9caf79 100644
--- a/wp-includes/class-wpdb.php
+++ b/wp-includes/class-wpdb.php
@@ -51,6 +51,7 @@ define( 'ARRAY_N', 'ARRAY_N' );
  *
  * @since 0.71
  */
+#[AllowDynamicProperties]
 class wpdb {
 
 	/**
diff --git a/wp-includes/class.wp-dependencies.php b/wp-includes/class.wp-dependencies.php
index c527715a63..1deb9a41fb 100644
--- a/wp-includes/class.wp-dependencies.php
+++ b/wp-includes/class.wp-dependencies.php
@@ -15,6 +15,7 @@
  *
  * @see _WP_Dependency
  */
+#[AllowDynamicProperties]
 class WP_Dependencies {
 	/**
 	 * An array of all registered dependencies keyed by handle.
diff --git a/wp-includes/customize/class-wp-customize-partial.php b/wp-includes/customize/class-wp-customize-partial.php
index f75ac43945..06502bec11 100644
--- a/wp-includes/customize/class-wp-customize-partial.php
+++ b/wp-includes/customize/class-wp-customize-partial.php
@@ -16,6 +16,7 @@
  *
  * @since 4.5.0
  */
+#[AllowDynamicProperties]
 class WP_Customize_Partial {
 
 	/**
diff --git a/wp-includes/customize/class-wp-customize-selective-refresh.php b/wp-includes/customize/class-wp-customize-selective-refresh.php
index e5e3bcbba5..6119e68944 100644
--- a/wp-includes/customize/class-wp-customize-selective-refresh.php
+++ b/wp-includes/customize/class-wp-customize-selective-refresh.php
@@ -12,6 +12,7 @@
  *
  * @since 4.5.0
  */
+#[AllowDynamicProperties]
 final class WP_Customize_Selective_Refresh {
 
 	/**
diff --git a/wp-includes/pomo/entry.php b/wp-includes/pomo/entry.php
index 55ff28680e..97ffe46b7b 100644
--- a/wp-includes/pomo/entry.php
+++ b/wp-includes/pomo/entry.php
@@ -11,6 +11,7 @@ if ( ! class_exists( 'Translation_Entry', false ) ) :
 	/**
 	 * Translation_Entry class encapsulates a translatable string.
 	 */
+	#[AllowDynamicProperties]
 	class Translation_Entry {
 
 		/**
diff --git a/wp-includes/pomo/plural-forms.php b/wp-includes/pomo/plural-forms.php
index 2ed0c62ebf..b072bfadac 100644
--- a/wp-includes/pomo/plural-forms.php
+++ b/wp-includes/pomo/plural-forms.php
@@ -6,6 +6,7 @@
  * @since 4.9.0
  */
 if ( ! class_exists( 'Plural_Forms', false ) ) :
+	#[AllowDynamicProperties]
 	class Plural_Forms {
 		/**
 		 * Operator characters.
diff --git a/wp-includes/pomo/streams.php b/wp-includes/pomo/streams.php
index 4f836961f4..5c1a95a2ed 100644
--- a/wp-includes/pomo/streams.php
+++ b/wp-includes/pomo/streams.php
@@ -9,6 +9,7 @@
  */
 
 if ( ! class_exists( 'POMO_Reader', false ) ) :
+	#[AllowDynamicProperties]
 	class POMO_Reader {
 
 		public $endian = 'little';
diff --git a/wp-includes/pomo/translations.php b/wp-includes/pomo/translations.php
index 6a69ebdb3b..8ebcbaa8d2 100644
--- a/wp-includes/pomo/translations.php
+++ b/wp-includes/pomo/translations.php
@@ -11,6 +11,7 @@ require_once __DIR__ . '/plural-forms.php';
 require_once __DIR__ . '/entry.php';
 
 if ( ! class_exists( 'Translations', false ) ) :
+	#[AllowDynamicProperties]
 	class Translations {
 		public $entries = array();
 		public $headers = array();
@@ -314,6 +315,7 @@ if ( ! class_exists( 'NOOP_Translations', false ) ) :
 	/**
 	 * Provides the same interface as Translations, but doesn't do anything
 	 */
+	#[AllowDynamicProperties]
 	class NOOP_Translations {
 		public $entries = array();
 		public $headers = array();
diff --git a/wp-includes/rest-api/class-wp-rest-request.php b/wp-includes/rest-api/class-wp-rest-request.php
index 87689a94a5..b93bd36857 100644
--- a/wp-includes/rest-api/class-wp-rest-request.php
+++ b/wp-includes/rest-api/class-wp-rest-request.php
@@ -26,6 +26,7 @@
  *
  * @link https://www.php.net/manual/en/class.arrayaccess.php
  */
+#[AllowDynamicProperties]
 class WP_REST_Request implements ArrayAccess {
 
 	/**
diff --git a/wp-includes/rest-api/class-wp-rest-server.php b/wp-includes/rest-api/class-wp-rest-server.php
index ede83bdb19..ddb3f6c01b 100644
--- a/wp-includes/rest-api/class-wp-rest-server.php
+++ b/wp-includes/rest-api/class-wp-rest-server.php
@@ -12,6 +12,7 @@
  *
  * @since 4.4.0
  */
+#[AllowDynamicProperties]
 class WP_REST_Server {
 
 	/**
diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
index 982376cb2f..61591cb6c1 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
@@ -12,6 +12,7 @@
  *
  * @since 4.7.0
  */
+#[AllowDynamicProperties]
 abstract class WP_REST_Controller {
 
 	/**
diff --git a/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php b/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php
index f186648545..1b6a7fe37f 100644
--- a/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php
+++ b/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php
@@ -12,6 +12,7 @@
  *
  * @since 4.7.0
  */
+#[AllowDynamicProperties]
 abstract class WP_REST_Meta_Fields {
 
 	/**
diff --git a/wp-includes/rest-api/search/class-wp-rest-search-handler.php b/wp-includes/rest-api/search/class-wp-rest-search-handler.php
index b2aa64e916..34ba2f1c08 100644
--- a/wp-includes/rest-api/search/class-wp-rest-search-handler.php
+++ b/wp-includes/rest-api/search/class-wp-rest-search-handler.php
@@ -12,6 +12,7 @@
  *
  * @since 5.0.0
  */
+#[AllowDynamicProperties]
 abstract class WP_REST_Search_Handler {
 
 	/**
diff --git a/wp-includes/sitemaps/class-wp-sitemaps-index.php b/wp-includes/sitemaps/class-wp-sitemaps-index.php
index 10348494f3..940358823f 100644
--- a/wp-includes/sitemaps/class-wp-sitemaps-index.php
+++ b/wp-includes/sitemaps/class-wp-sitemaps-index.php
@@ -15,6 +15,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 class WP_Sitemaps_Index {
 	/**
 	 * The main registry of supported sitemaps.
diff --git a/wp-includes/sitemaps/class-wp-sitemaps-provider.php b/wp-includes/sitemaps/class-wp-sitemaps-provider.php
index 415ce66ebc..81464c1bdb 100644
--- a/wp-includes/sitemaps/class-wp-sitemaps-provider.php
+++ b/wp-includes/sitemaps/class-wp-sitemaps-provider.php
@@ -14,6 +14,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 abstract class WP_Sitemaps_Provider {
 	/**
 	 * Provider name.
diff --git a/wp-includes/sitemaps/class-wp-sitemaps-registry.php b/wp-includes/sitemaps/class-wp-sitemaps-registry.php
index 6edf1dfe5c..4775ae5da1 100644
--- a/wp-includes/sitemaps/class-wp-sitemaps-registry.php
+++ b/wp-includes/sitemaps/class-wp-sitemaps-registry.php
@@ -14,6 +14,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 class WP_Sitemaps_Registry {
 	/**
 	 * Registered sitemap providers.
diff --git a/wp-includes/sitemaps/class-wp-sitemaps-renderer.php b/wp-includes/sitemaps/class-wp-sitemaps-renderer.php
index 0069b11126..11d5c3820a 100644
--- a/wp-includes/sitemaps/class-wp-sitemaps-renderer.php
+++ b/wp-includes/sitemaps/class-wp-sitemaps-renderer.php
@@ -14,6 +14,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 class WP_Sitemaps_Renderer {
 	/**
 	 * XSL stylesheet for styling a sitemap for web browsers.
diff --git a/wp-includes/sitemaps/class-wp-sitemaps-stylesheet.php b/wp-includes/sitemaps/class-wp-sitemaps-stylesheet.php
index 3051900065..8268fcc924 100644
--- a/wp-includes/sitemaps/class-wp-sitemaps-stylesheet.php
+++ b/wp-includes/sitemaps/class-wp-sitemaps-stylesheet.php
@@ -14,6 +14,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 class WP_Sitemaps_Stylesheet {
 	/**
 	 * Renders the XSL stylesheet depending on whether it's the sitemap index or not.
diff --git a/wp-includes/sitemaps/class-wp-sitemaps.php b/wp-includes/sitemaps/class-wp-sitemaps.php
index 2e96e48ed2..cd8d1e4dbc 100644
--- a/wp-includes/sitemaps/class-wp-sitemaps.php
+++ b/wp-includes/sitemaps/class-wp-sitemaps.php
@@ -14,6 +14,7 @@
  *
  * @since 5.5.0
  */
+#[AllowDynamicProperties]
 class WP_Sitemaps {
 	/**
 	 * The main index of supported sitemaps.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index e3d8ab83d4..c304864534 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-54132';
+$wp_version = '6.1-alpha-54133';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.