wp-includes/formatting.php:3284Adds rel="nofollow ugc" string to all HTML A elements in content.
$textstringstringfunction wp_rel_ugc( $text ) { // This is a pre-save filter, so text is already escaped. $text = stripslashes( $text ); $text = preg_replace_callback( '|<a (.+?)>|i', static function ( $matches ) { return wp_rel_callback( $matches, 'nofollow ugc' ); }, $text ); return wp_slash( $text );}Introduced in 5.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/formatting.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.