Pre AI and Post AI code review hours are both 0.75 in this made up example. I find that implausible.
Even with the same amount of code, AI code is less trustworthy* and requires more attention... but we know it won't be the same amount, it will be more. This means it will take longer to review, or there will be unforeseen consequences of not spending that extra time.
*meaning no human eyes have looked at it and said "this doesn't make sense", or "this is cheating", or "this doesn't meet requirements", and won't be caught until code review if at all.
The hard part is that LLM code looks like there is some sort of flow. It is like a nice statistical smooth flow. It looks very convincing at a glance. No one would write code like that and not know what they are doing comments self assured and all.
To me the biggest gotcha with AI code is that the bugs are not “normal”.
When reviewing human code I focus on specific parts because I know that there are parts where a person will just not make a bug (unless very junior).
AI on the other hand, will not do an off-by-one mistake, but it will happily just delete perfectly working code for no obvious reason. Or monkey patch a dependency because it missed a config flag. Or generally fail in a very novel and creative way.
The effort it takes to review AI code is much greater. And this is in a code base I am deeply familiar with.
Imo the future lies in a solid core programs with powerful plugin frameworks that expect all plugins to be code that was never read.