This is the answer, and it has been the answer going back to the before times when we didn't have pull requests but we did in-person team code reviews before merging branches (yes, really). A massive, complicated merge without documentation and extensive support from other interested/impacted people and teams justifying things like a parser DSL? That is always going to be a problem whether AI generated it or the developer locked their office door and went on a three-day manic coding binge.

AI doesn't directly make this stuff worse, it accelerates a team's journey towards embracing engineering practices around the code being written by humans or LLMs.