diff --git a/wp-admin/includes/class-walker-category-checklist.php b/wp-admin/includes/class-walker-category-checklist.php
index 90ee40f834..b86ba23a2b 100644
--- a/wp-admin/includes/class-walker-category-checklist.php
+++ b/wp-admin/includes/class-walker-category-checklist.php
@@ -125,13 +125,14 @@ class Walker_Category_Checklist extends Walker {
 	 * @see Walker::end_el()
 	 *
 	 * @since 2.5.1
+	 * @since 5.9.0 Renamed `$category` to `$data_object` to match parent class for PHP 8 named parameter support.
 	 *
-	 * @param string  $output   Used to append additional content (passed by reference).
-	 * @param WP_Term $category The current term object.
-	 * @param int     $depth    Depth of the term in reference to parents. Default 0.
-	 * @param array   $args     An array of arguments. @see wp_terms_checklist()
+	 * @param string  $output      Used to append additional content (passed by reference).
+	 * @param WP_Term $data_object The current term object.
+	 * @param int     $depth       Depth of the term in reference to parents. Default 0.
+	 * @param array   $args        An array of arguments. @see wp_terms_checklist()
 	 */
-	public function end_el( &$output, $category, $depth = 0, $args = array() ) {
+	public function end_el( &$output, $data_object, $depth = 0, $args = array() ) {
 		$output .= "</li>\n";
 	}
 }
diff --git a/wp-includes/class-walker-category.php b/wp-includes/class-walker-category.php
index 43bb7c69cf..fcf54a333f 100644
--- a/wp-includes/class-walker-category.php
+++ b/wp-includes/class-walker-category.php
@@ -254,16 +254,17 @@ class Walker_Category extends Walker {
 	 * Ends the element output, if needed.
 	 *
 	 * @since 2.1.0
+	 * @since 5.9.0 Renamed `$page` to `$data_object` to match parent class for PHP 8 named parameter support.
 	 *
 	 * @see Walker::end_el()
 	 *
-	 * @param string $output Used to append additional content (passed by reference).
-	 * @param object $page   Not used.
-	 * @param int    $depth  Optional. Depth of category. Not used.
-	 * @param array  $args   Optional. An array of arguments. Only uses 'list' for whether should append
-	 *                       to output. See wp_list_categories(). Default empty array.
+	 * @param string $output      Used to append additional content (passed by reference).
+	 * @param object $data_object Category data object. Not used.
+	 * @param int    $depth       Optional. Depth of category. Not used.
+	 * @param array  $args        Optional. An array of arguments. Only uses 'list' for whether should
+	 *                            append to output. See wp_list_categories(). Default empty array.
 	 */
-	public function end_el( &$output, $page, $depth = 0, $args = array() ) {
+	public function end_el( &$output, $data_object, $depth = 0, $args = array() ) {
 		if ( 'list' !== $args['style'] ) {
 			return;
 		}
diff --git a/wp-includes/class-walker-comment.php b/wp-includes/class-walker-comment.php
index bf00996028..1a81a0b5d1 100644
--- a/wp-includes/class-walker-comment.php
+++ b/wp-includes/class-walker-comment.php
@@ -213,19 +213,25 @@ class Walker_Comment extends Walker {
 	 * Ends the element output, if needed.
 	 *
 	 * @since 2.7.0
+	 * @since 5.9.0 Renamed `$comment` to `$data_object` to match parent class for PHP 8 named parameter support.
 	 *
 	 * @see Walker::end_el()
 	 * @see wp_list_comments()
 	 *
-	 * @param string     $output  Used to append additional content. Passed by reference.
-	 * @param WP_Comment $comment The current comment object. Default current comment.
-	 * @param int        $depth   Optional. Depth of the current comment. Default 0.
-	 * @param array      $args    Optional. An array of arguments. Default empty array.
+	 * @param string     $output      Used to append additional content. Passed by reference.
+	 * @param WP_Comment $data_object Comment data object.
+	 * @param int        $depth       Optional. Depth of the current comment. Default 0.
+	 * @param array      $args        Optional. An array of arguments. Default empty array.
 	 */
-	public function end_el( &$output, $comment, $depth = 0, $args = array() ) {
+	public function end_el( &$output, $data_object, $depth = 0, $args = array() ) {
 		if ( ! empty( $args['end-callback'] ) ) {
 			ob_start();
-			call_user_func( $args['end-callback'], $comment, $args, $depth );
+			call_user_func(
+				$args['end-callback'],
+				$data_object, // The current comment object.
+				$args,
+				$depth
+			);
 			$output .= ob_get_clean();
 			return;
 		}
diff --git a/wp-includes/class-walker-nav-menu.php b/wp-includes/class-walker-nav-menu.php
index 3fdc8d8c4b..fad796005c 100644
--- a/wp-includes/class-walker-nav-menu.php
+++ b/wp-includes/class-walker-nav-menu.php
@@ -256,15 +256,16 @@ class Walker_Nav_Menu extends Walker {
 	 * Ends the element output, if needed.
 	 *
 	 * @since 3.0.0
+	 * @since 5.9.0 Renamed `$item` to `$data_object` to match parent class for PHP 8 named parameter support.
 	 *
 	 * @see Walker::end_el()
 	 *
-	 * @param string   $output Used to append additional content (passed by reference).
-	 * @param WP_Post  $item   Page data object. Not used.
-	 * @param int      $depth  Depth of page. Not Used.
-	 * @param stdClass $args   An object of wp_nav_menu() arguments.
+	 * @param string   $output      Used to append additional content (passed by reference).
+	 * @param WP_Post  $data_object Menu item data object. Not used.
+	 * @param int      $depth       Depth of page. Not Used.
+	 * @param stdClass $args        An object of wp_nav_menu() arguments.
 	 */
-	public function end_el( &$output, $item, $depth = 0, $args = null ) {
+	public function end_el( &$output, $data_object, $depth = 0, $args = null ) {
 		if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
 			$t = '';
 			$n = '';
diff --git a/wp-includes/class-walker-page.php b/wp-includes/class-walker-page.php
index daa162d74b..ad443dc2a6 100644
--- a/wp-includes/class-walker-page.php
+++ b/wp-includes/class-walker-page.php
@@ -222,15 +222,16 @@ class Walker_Page extends Walker {
 	 * Outputs the end of the current element in the tree.
 	 *
 	 * @since 2.1.0
+	 * @since 5.9.0 Renamed `$page` to `$data_object` to match parent class for PHP 8 named parameter support.
 	 *
 	 * @see Walker::end_el()
 	 *
-	 * @param string  $output Used to append additional content. Passed by reference.
-	 * @param WP_Post $page   Page data object. Not used.
-	 * @param int     $depth  Optional. Depth of page. Default 0 (unused).
-	 * @param array   $args   Optional. Array of arguments. Default empty array.
+	 * @param string  $output      Used to append additional content. Passed by reference.
+	 * @param WP_Post $data_object Page data object. Not used.
+	 * @param int     $depth       Optional. Depth of page. Default 0 (unused).
+	 * @param array   $args        Optional. Array of arguments. Default empty array.
 	 */
-	public function end_el( &$output, $page, $depth = 0, $args = array() ) {
+	public function end_el( &$output, $data_object, $depth = 0, $args = array() ) {
 		if ( isset( $args['item_spacing'] ) && 'preserve' === $args['item_spacing'] ) {
 			$t = "\t";
 			$n = "\n";
diff --git a/wp-includes/class-wp-walker.php b/wp-includes/class-wp-walker.php
index 9e39777579..b50c2d7505 100644
--- a/wp-includes/class-wp-walker.php
+++ b/wp-includes/class-wp-walker.php
@@ -100,14 +100,15 @@ class Walker {
 	 * The $args parameter holds additional values that may be used with the child class methods.
 	 *
 	 * @since 2.1.0
+	 * @since 5.9.0 Renamed `$object` (a PHP reserved keyword) to `$data_object` for PHP 8 named parameter support.
 	 * @abstract
 	 *
-	 * @param string $output Used to append additional content (passed by reference).
-	 * @param object $object The data object.
-	 * @param int    $depth  Depth of the item.
-	 * @param array  $args   An array of additional arguments.
+	 * @param string $output      Used to append additional content (passed by reference).
+	 * @param object $data_object The data object.
+	 * @param int    $depth       Depth of the item.
+	 * @param array  $args        An array of additional arguments.
 	 */
-	public function end_el( &$output, $object, $depth = 0, $args = array() ) {}
+	public function end_el( &$output, $data_object, $depth = 0, $args = array() ) {}
 
 	/**
 	 * Traverse elements to create list from elements.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index eafa858ba8..cf8a23499f 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51779';
+$wp_version = '5.9-alpha-51780';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.