I really liked codex in the last few weeks, especially its ability to clean up after Claude's (prose) messes and do reviews.

But in the last few days something seems to have happened that made Codex's models massively stupider (for what I am doing).

Really weirdly, it suddenly refused to even run tests it previously wrote itself (and previously ran), because of some false positive about cybersecurity.

That by itself is not evidence of stupidity. Trying to make a 200+ file PR full of research notes is, and the PR didn't even solve the problem I asked it to.