Ticket #54013: 54013.diff

src/wp-includes/block-supports/layout.php

@@ -118 +118 @@
  * @return string Filtered block content.
  */
 function wp_restore_group_inner_container( $block_content, $block ) {
-        $group_with_inner_container_regex = '/(^\s*<div\b[^>]*wp-block-group(\s|")[^>]*>)(\s*<div\b[^>]*wp-block-group__inner-container(\s|")[^>]*>)((.|\S|\s)*)/';
+        $group_with_inner_container_regex = '/(^\s*<div\b[^>]*wp-block-group(\s|")[^>]*>)(\s*<div\b[^>]*wp-block-group__inner-container(\s|")[^>]*>)((.|\S|\s)*)/U';
 
         if (
                 'core/group' !== $block['blockName'] ||