delete_post hook – deleting multiple items

That’s not how that hook is meant to be used:

do_action( 'delete_post', int $postid, WP_Post $post )

https://developer.wordpress.org/reference/hooks/delete_post/

The action gives you the post ID and a post object.

So don’t access $_GET or the global $post object, instead use the what the action gives you.

tech