AI coding tools are pretty good at finding bugs and make it easier and faster to fix them.
Importantly, security vulnerabilities in new releases seem to stay roughly the same and the change to which bugs count as CVEs was around version 6.8 already.
Those other projects are not at high quality control like Linux. They probably vibe slop it and introduce a lot of regressions. Such data would be interesting on Linux too, just to have some comparison. But I don't think it's exploding regressions, as there is no indication for that so far.