Perhaps the velocity is the problem, not that AI inherently produces worse code (you just need one bad or just inexperienced engineer have their PR slip through to have bad human written code in you code base). When the velocity is high, there's less time to battle test each change and new code piles up on the old one. When the velocity is low, shitty code fails in production, but people are aware of what was recently changed and can find and fix the problems.