EA anticheat is a kernel level anticheat, which are generally bad for consumers due to them giving malware new targets to get full control of an infected system. Genshin Impact’s kernel anticheat is famously targeted by ransomware as an easier way to gain control of user’s PCs for example. They also don’t work on Linux, which is an obvious problem for Steam Deck users.
I guess if you want to accurately want to do the checks on the server side you’d have to run the complete game on the server. You can cheat just by making a texture transparent so that you can see enemies behind it. To prevent that the server has to render the frames itself and to ensure that really only approved things are seen by the players the easiest would be to just send over the rendered frame instead of letting the players render it themselves. By that point you have basically invented game streaming again.
Still, I wonder what Blizzard games are doing. They work fine on Linux and I haven’t heard much about cheating on there.
You don’t have to send over the frame to fix it a bit, just less information. Minimize the info needed. One thing you can do is occlude to determine which entities should be rendered. Even applied, they could still get an advantage - being able to see an entire character instead of just the exposed part of their foot - but it would at least limit it more.
It seems like VAC has solved the binary editing issue a while ago, no?