Collabora, one of the companies working under contract for Valve to help improve Windows game emulation on Linux with the likes of Wine have now sent in some patches to the Linux Kernel mailing list for discussion.
This is going to be another big step forward for compatibility, hopefully, to help with the likes of anti-tamper and DRM which often skip over the Windows API which causes issues for Linux and the Wine compatibility layer (and so Steam Play Proton too). You can get an overview of it in this previous article and also this article if you want some background on it all. To be clear: a Valve developer did mention it's not for anti-cheat.
With this new feature they're calling "Syscall User Dispatch (SUD)" it allows to "efficiently redirect system calls of only part of a binary back to userspace to be emulated by a compatibility layer". The patches are now close to being accepted but they wanted to get a bit more discussion going to ensure the majority are happy with it.
If accepted, it would still take some time before the likes of Wine and Proton would really make use of it, especially as it would also require users to have a much more up to date Linux Kernel too.