I think Martin Fowler's "Refactoring" might give a bit of insight here. One of my take-aways after reading that book is that the specific implementation of a function is not very important if you have tests. He argues that it can sometimes be easier to completely re-write a function than to take the time to understand it - as long as you can validate that your re-write performs the same way. This mindset lines up pretty closely with how I've been using LLMs.

If that's true, then I would think the emphasis in code review should be more on test quality and verifying that the spec is captured accurately, and as you suggest, the actual implementation is less important.