diff --git a/wp-includes/kses.php b/wp-includes/kses.php
index 03a4881fb3..b32df1beaa 100644
--- a/wp-includes/kses.php
+++ b/wp-includes/kses.php
@@ -820,6 +820,10 @@ function wp_kses_allowed_html( $context = '' ) {
 		/**
 		 * Filters the HTML tags that are allowed for a given context.
 		 *
+		 * HTML tags and attribute names are case-insensitive in HTML but must be
+		 * added to the KSES allow list in lowercase. An item added to the allow list
+		 * in upper or mixed case will not recognized as permitted by KSES.
+		 *
 		 * @since 3.5.0
 		 *
 		 * @param array[] $html    Allowed HTML tags.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2ab45982ae..f5a1213f50 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-alpha-53033';
+$wp_version = '6.0-alpha-53034';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.