This is a really old idea. It was implemented in CS:GO in ~2015 [0], although community anti-cheats like SMAC have implemented it for years before then [1]. Riot have an article about their implementation of the same idea in VALORANT's that a good read from a technical perspective [2].

Sadly, CS2, from what I've gathered, broke this.

[0]: https://www.reddit.com/r/GlobalOffensive/comments/35zwwy/opt...

[1]: https://www.youtube.com/watch?v=qkhQgYB4lAA

[2]: https://technology.riotgames.com/news/demolishing-wallhacks-...