revision id is one number behind – publish_post
See this- function check_values( $post_ID, $post ) { $revisions = wp_get_post_revisions( $post_ID ); $revision_ids = []; foreach ( $revisions as $revision ) { $revision_ids[] = $revision->ID; } // $revision_ids; // holds all revision ids // $revision_ids[0]; // latest revision // $revision_ids[1]; //revision just before the latest one } add_action( ‘publish_post’, ‘check_values’, 10, 2 );