"VAC" is a catch-all term for all of Valve's anti-cheating mechanisms.
The primary one is a standard user-mode software module, that does traditional scanning.
The AI mechanism you're referring to is these days referred to as "VAC Live" (previously, VACNet). The primary game it is deployed on is Counter-Strike 2. From what we understand, it is a very game-dependent stack, so it is not universally deploy-able.
One of my recent thoughts is that Claude Code has become the most successful agent partially because it is more of a black box than previous implementations of the agent pattern: the actual code changes aren't shoved in your face like Cursor (used to be), they are hidden away. You focus more on the result rather than the code building up that result, and so you get into the "just one more feature" mindset a lot more, because you're never concerned that the code you're building is sloppy.
It's because claude code will test its work and adjust the code accordingly. The old way, with the way Cursor used to be or the way I used to copy and paste code from ChatGPT doesn't work because to iterate in towards a working solution requires too much human effort, making the whole thing pointless.
Anecdata here, but the last times I tried to use VISA/MasterCard in a shopping mall meant to serve people from all over the world, it just did not work. UPI was flawless, though.
(And then as pointed out, anyone smaller straight up doesn’t support anything outside of UPI.)
Worth noting that part of the packet size appears to be due to animation data, which they’ve begun the process of transitioning to a more efficient system. [0]
With that being said: totally agree on the netcode.
CS2 is 64 tick under the hood, with interpolation between the ticks. In the beta, server operators could modify the tick rate by patching the server binary, but when that revealed inconsistencies (which was meant to be avoided with the "subtick" system), they hard coded the client side tick rate to 64 [0].
[0]: https://steamdb.info/patchnotes/14178987/