Looks like a bug. The second screenshot is saying that they’ve been deleted, and that they should have been permanently deleted 548 days ago. The 4GB is probably stuck in some sort of recycle bin. Maybe try undoing the delete, and delete again.
That’s a negative number. It says -548 days. I’m guessing you turned off Messages in iCloud about a year and a half ago? It should have permanently deleted the messages 30 days after that.