As of PHP 8.1, explode() does not permit null as its second argument. This results in warnings being spat out on every page because of a usage of this in wp-includes/block-supports/layout.php. See #53635. Props noisysocks. Built from https://develop.svn.wordpress.org/trunk@52380 git-svn-id: http://core.svn.wordpress.org/trunk@51972 1a063a9b-81f0-0310-95a4-ce76da25c4cd