diff --git a/wp-includes/class-wp-block-list.php b/wp-includes/class-wp-block-list.php
index 378faba578..2b0750bfee 100644
--- a/wp-includes/class-wp-block-list.php
+++ b/wp-includes/class-wp-block-list.php
@@ -72,6 +72,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 * @param string $index Index of block to check.
 	 * @return bool Whether block exists.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetExists( $index ) {
 		return isset( $this->blocks[ $index ] );
 	}
@@ -86,6 +87,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 * @param string $index Index of block value to retrieve.
 	 * @return mixed|null Block value if exists, or null.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetGet( $index ) {
 		$block = $this->blocks[ $index ];
 
@@ -107,6 +109,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 * @param string $index Index of block value to set.
 	 * @param mixed  $value Block value.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetSet( $index, $value ) {
 		if ( is_null( $index ) ) {
 			$this->blocks[] = $value;
@@ -124,6 +127,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 *
 	 * @param string $index Index of block value to unset.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetUnset( $index ) {
 		unset( $this->blocks[ $index ] );
 	}
@@ -135,6 +139,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 *
 	 * @link https://www.php.net/manual/en/iterator.rewind.php
 	 */
+	#[ReturnTypeWillChange]
 	public function rewind() {
 		reset( $this->blocks );
 	}
@@ -148,6 +153,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 *
 	 * @return mixed Current element.
 	 */
+	#[ReturnTypeWillChange]
 	public function current() {
 		return $this->offsetGet( $this->key() );
 	}
@@ -161,6 +167,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 *
 	 * @return mixed Key of the current element.
 	 */
+	#[ReturnTypeWillChange]
 	public function key() {
 		return key( $this->blocks );
 	}
@@ -172,6 +179,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 *
 	 * @link https://www.php.net/manual/en/iterator.next.php
 	 */
+	#[ReturnTypeWillChange]
 	public function next() {
 		next( $this->blocks );
 	}
@@ -183,6 +191,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 *
 	 * @link https://www.php.net/manual/en/iterator.valid.php
 	 */
+	#[ReturnTypeWillChange]
 	public function valid() {
 		return null !== key( $this->blocks );
 	}
@@ -196,6 +205,7 @@ class WP_Block_List implements Iterator, ArrayAccess, Countable {
 	 *
 	 * @return int Block count.
 	 */
+	#[ReturnTypeWillChange]
 	public function count() {
 		return count( $this->blocks );
 	}
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 01f1b12f9f..aa9217cc06 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51531';
+$wp_version = '5.9-alpha-51532';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.