I review PRs primarily for correctness and to look for nonobvious problems. I rarely find buggy code. Sometimes I'll find performance issues. In order to do what I do when reviewing, ChatGPT would need clear specs (yeah right) and a deep understanding of our system, domain, and even our customers.

Of course I'll try it and see how it does. But it struggled and failed to produce what I would consider trivial code when I tried to create a single usable page to spec in react native, so I'm not terribly optimistic.