Unfortunately, only a single PR like this comes to mind. Most AI authors we've seen were identifiable mainly by overly verbose PR descriptions, meaningless code changes and copy-pasting more AI output when questioned.
A contributor in good faith is going to accept criticism and resubmit an improved change: less files modified, more explanation, more focus, references to actual tickets and discussion with actual developers.
… but still unfortunately leaves reviewers having to spend time checking submissions and rejecting them.