diff -r 7b1b88e27a20 -r 48c4eec2b7e6 wp/wp-includes/blocks/pattern.php
--- a/wp/wp-includes/blocks/pattern.php	Thu Sep 29 08:06:27 2022 +0200
+++ b/wp/wp-includes/blocks/pattern.php	Fri Sep 05 18:40:08 2025 +0200
@@ -8,7 +8,7 @@
 /**
  *  Registers the `core/pattern` block on the server.
  *
- * @return void
+ * @since 5.9.0
  */
 function register_block_core_pattern() {
 	register_block_type_from_metadata(
@@ -22,23 +22,58 @@
 /**
  * Renders the `core/pattern` block on the server.
  *
+ * @since 6.3.0 Backwards compatibility: blocks with no `syncStatus` attribute do not receive block wrapper.
+ *
+ * @global WP_Embed $wp_embed Used to process embedded content within patterns
+ *
  * @param array $attributes Block attributes.
  *
  * @return string Returns the output of the pattern.
  */
 function render_block_core_pattern( $attributes ) {
+	static $seen_refs = array();
+
 	if ( empty( $attributes['slug'] ) ) {
 		return '';
 	}
 
 	$slug     = $attributes['slug'];
 	$registry = WP_Block_Patterns_Registry::get_instance();
+
 	if ( ! $registry->is_registered( $slug ) ) {
 		return '';
 	}
 
+	if ( isset( $seen_refs[ $attributes['slug'] ] ) ) {
+		// WP_DEBUG_DISPLAY must only be honored when WP_DEBUG. This precedent
+		// is set in `wp_debug_mode()`.
+		$is_debug = WP_DEBUG && WP_DEBUG_DISPLAY;
+
+		return $is_debug ?
+			// translators: Visible only in the front end, this warning takes the place of a faulty block. %s represents a pattern's slug.
+			sprintf( __( '[block rendering halted for pattern "%s"]' ), $slug ) :
+			'';
+	}
+
 	$pattern = $registry->get_registered( $slug );
-	return do_blocks( $pattern['content'] );
+	$content = $pattern['content'];
+
+	// Backward compatibility for handling Block Hooks and injecting the theme attribute in the Gutenberg plugin.
+	// This can be removed when the minimum supported WordPress is >= 6.4.
+	if ( defined( 'IS_GUTENBERG_PLUGIN' ) && IS_GUTENBERG_PLUGIN && ! function_exists( 'traverse_and_serialize_blocks' ) ) {
+		$blocks  = parse_blocks( $content );
+		$content = gutenberg_serialize_blocks( $blocks );
+	}
+
+	$seen_refs[ $attributes['slug'] ] = true;
+
+	$content = do_blocks( $content );
+
+	global $wp_embed;
+	$content = $wp_embed->autoembed( $content );
+
+	unset( $seen_refs[ $attributes['slug'] ] );
+	return $content;
 }
 
 add_action( 'init', 'register_block_core_pattern' );