diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-block-pattern-categories-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-block-pattern-categories-controller.php
index f8a6c0c190fff..36a753416013f 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-block-pattern-categories-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-block-pattern-categories-controller.php
@@ -125,6 +125,10 @@ public function prepare_item_for_response( $item, $request ) {
 	 * @return array Item schema data.
 	 */
 	public function get_item_schema() {
+		if ( $this->schema ) {
+			return $this->add_additional_fields_schema( $this->schema );
+		}
+
 		$schema = array(
 			'$schema'    => 'http://json-schema.org/draft-04/schema#',
 			'title'      => 'block-pattern-category',
@@ -151,6 +155,8 @@ public function get_item_schema() {
 			),
 		);
 
-		return $this->add_additional_fields_schema( $schema );
+		$this->schema = $schema;
+
+		return $this->add_additional_fields_schema( $this->schema );
 	}
 }
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-block-patterns-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-block-patterns-controller.php
index 3acaefdf2cab8..d8f083924e030 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-block-patterns-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-block-patterns-controller.php
@@ -199,6 +199,10 @@ public function prepare_item_for_response( $item, $request ) {
 	 * @return array Item schema data.
 	 */
 	public function get_item_schema() {
+		if ( $this->schema ) {
+			return $this->add_additional_fields_schema( $this->schema );
+		}
+
 		$schema = array(
 			'$schema'    => 'http://json-schema.org/draft-04/schema#',
 			'title'      => 'block-pattern',
@@ -287,6 +291,8 @@ public function get_item_schema() {
 			),
 		);
 
-		return $this->add_additional_fields_schema( $schema );
+		$this->schema = $schema;
+
+		return $this->add_additional_fields_schema( $this->schema );
 	}
 }
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-blocks-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-blocks-controller.php
index 4a316685e1556..cd2e63d7c5b22 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-blocks-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-blocks-controller.php
@@ -67,6 +67,10 @@ public function filter_response_by_context( $data, $context ) {
 	 * @return array Item schema data.
 	 */
 	public function get_item_schema() {
+		if ( $this->schema ) {
+			return $this->add_additional_fields_schema( $this->schema );
+		}
+
 		// Do not cache this schema because all properties are derived from parent controller.
 		$schema = parent::get_item_schema();
 
@@ -86,7 +90,9 @@ public function get_item_schema() {
 		unset( $schema['properties']['title']['properties']['rendered'] );
 		unset( $schema['properties']['content']['properties']['rendered'] );
 
-		return $schema;
+		$this->schema = $schema;
+
+		return $this->add_additional_fields_schema( $this->schema );
 	}
 
 }
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-menu-items-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-menu-items-controller.php
index 59edfa5bcd7b8..940e0702df49c 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-menu-items-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-menu-items-controller.php
@@ -710,6 +710,10 @@ protected function get_schema_links() {
 	 * @return array Item schema data.
 	 */
 	public function get_item_schema() {
+		if ( $this->schema ) {
+			return $this->add_additional_fields_schema( $this->schema );
+		}
+
 		$schema = array(
 			'$schema' => 'http://json-schema.org/draft-04/schema#',
 			'title'   => $this->post_type,
@@ -914,7 +918,9 @@ public function get_item_schema() {
 			$schema['links'] = $schema_links;
 		}
 
-		return $this->add_additional_fields_schema( $schema );
+		$this->schema = $schema;
+
+		return $this->add_additional_fields_schema( $this->schema );
 	}
 
 	/**
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-menus-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-menus-controller.php
index 18b2c8fcfd204..719377db8f553 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-menus-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-menus-controller.php
@@ -523,6 +523,10 @@ protected function handle_locations( $menu_id, $request ) {
 	 * @return array Item schema data.
 	 */
 	public function get_item_schema() {
+		if ( $this->schema ) {
+			return $this->add_additional_fields_schema( $this->schema );
+		}
+
 		$schema = parent::get_item_schema();
 		unset( $schema['properties']['count'], $schema['properties']['link'], $schema['properties']['taxonomy'] );
 
@@ -566,6 +570,8 @@ public function get_item_schema() {
 			'type'        => 'boolean',
 		);
 
-		return $schema;
+		$this->schema = $schema;
+
+		return $this->add_additional_fields_schema( $this->schema );
 	}
 }