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.
And to be clear, that list is far from complete.
There are loads of steam games without DRM and those that use DRM mostly use the Steam provided one that sucks if one actually wants to crack it. It basically only protects against casual copy attempts.
Removed by mod