Yep. We've had to throw PRs away and ask them to start over with a smaller set of changes since it became impossible to manage. Reviews went on for weeks. The individual couldn't justify why things were done (and apparently their AI couldn't, either!)
Luckily those I work with are smart enough that I've not seen a PR thrown away yet, but sometimes I'm approving with more "meh, it's fine I guess" than "yeah, that makes sense".