See https://github.com/Swival/security-audits/ for examples, which are automated security audits just made with swival.dev /audit command, and includes audits of large code bases such as the entire OpenBSD base system.
To put it a different way, we now have roughly three times as many eyes rendering our bugs shallow. Or, to use the framing of the article, AI doubled the number, Mythos added another 50% on top.
This article is purely qualitative, but the quantative stuff matters.