Recently there was a thing where VAC would erroneously flag AMD’s antilag+ feature as cheating, and issue a ban.
AMD then quickly disabled the feature by default but now Valve also patched detection for it and is now, at least according to these patch notes, reversing the bans.
I agree. You don’t ship software that alters a competitive game’s DLLs without spending 5 minutes to discuss potential side effects. This was a major oversight.