diff -r be944660c56a -r 3d72ae0968f4 wp/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
--- a/wp/wp-includes/rest-api/endpoints/class-wp-rest-controller.php	Wed Sep 21 18:19:35 2022 +0200
+++ b/wp/wp-includes/rest-api/endpoints/class-wp-rest-controller.php	Tue Sep 27 16:37:53 2022 +0200
@@ -504,11 +504,14 @@
 	 *
 	 * @since 4.7.0
 	 *
+	 * @global array $wp_rest_additional_fields Holds registered fields, organized by object type.
+	 *
 	 * @param string $object_type Optional. The object type.
-	 * @return array Registered additional fields (if any), empty array if none or if the object type could
-	 *               not be inferred.
+	 * @return array Registered additional fields (if any), empty array if none or if the object type
+	 *               could not be inferred.
 	 */
 	protected function get_additional_fields( $object_type = null ) {
+		global $wp_rest_additional_fields;
 
 		if ( ! $object_type ) {
 			$object_type = $this->get_object_type();
@@ -518,8 +521,6 @@
 			return array();
 		}
 
-		global $wp_rest_additional_fields;
-
 		if ( ! $wp_rest_additional_fields || ! isset( $wp_rest_additional_fields[ $object_type ] ) ) {
 			return array();
 		}
@@ -596,7 +597,7 @@
 		// Return the list of all requested fields which appear in the schema.
 		return array_reduce(
 			$requested_fields,
-			function( $response_fields, $field ) use ( $fields ) {
+			static function( $response_fields, $field ) use ( $fields ) {
 				if ( in_array( $field, $fields, true ) ) {
 					$response_fields[] = $field;
 					return $response_fields;