Setting your mouse DPI settings too high? That's a ban.
An explosion in the game Counter-Strike 2.

Valve Anti-Cheat (VAC) hasn't been doing too hot lately. First, the anti-cheat issued bans to those using AMD's Anti-Lag+ feature in Counter-Strike 2. Now, VAC is issuing bans for setting your mouse DPI too high.

The issue with Anti-Lag+ was due to how AMD implemented the feature into a variety of games. It altered or hooked into game files, which is a big no-no when it comes to playing games that are supported by VAC. To Valve's credit, they did start to unban those impacted users after AMD pulled the video driver that introduced Anti-Lag+ to Counter-Strike 2.

This week, the issue with VAC is that it's issuing bans if you set your mouse DPI to something ridiculously high, say 10,000 or above, and spinning the camera around. Yes, that seems to be all it takes to get banned by VAC. While these DPI settings are several times higher than what anybody would ever reasonably use, it's not uncommon to set a super high DPI to screw around with before a round starts. Hell, I do it sometimes in games that aren't Counter-Strike 2 when just messing around with friends or before rounds fully begin. I'm sure many of us have done this in games.

The issue started to appear on r/GlobalOffensive over the past couple of days.

I was playing casual with some friends, we were shooting each other in the head with Negevs in warmup, and I hit my dpi button to spin as fast as possible so my character model would look ridiculous while reloading. By the end of warmup I was vac banned.
Reddit user Somethingese posted about their experience with the high DPI setting leading to a ban. They then provided a video with various timestamps showing how this issue can be easily reproduced.

In addition, a thread on the Counter-Strike 2 Steam Discussions has generated almost 19 pages of discussions by others who have also reportedly been struck with a VAC ban just for setting their mouse DPI settings too high. Then just a day ago, a YouTube user named TabbyN Dump, shared their own video where they were able to snag a VAC ban for setting their DPI settings too high.

Valve has not issued any sort of statement on these VAC bans. If they find that their anti-cheat is leading to false positives simply for using a high DPI setting, it would not be unreasonable to think that these bans will be reversed. Until then, it would be wise to avoid setting your mouse DPI to too high of a number and spinning around like a lunatic in Counter-Strike 2 until this issue is fixed.