I think It might've been last year but anti-cheat compatibility was huge. Still up to the studio to enable it but some games have.
Progress towards wayland is going steady which doesn't mean much to those that don't know much about Linux. But what that means is more modern features like VRR and HDR. Not completely here yet as far as I know but that wouldn't have happened on X11
Note exactly a huge milestone but you can't discredit the steady development of pipewire. Audio was annoying as fuck before it.
Honestly, I think we're 3 years out from Windows being replacable for a gaming platform.
Anti-cheat is a big one (sure, there's "support", but if none of the games people play are supported, is that support?), but VRR and HDR are also huge.
That trifecta is the only reason I'm still sitting in Windows, and I find myself hopeful we land there sooner rather than later so I can dump Windows and never have to think about whatever dumb crap Microsoft is going to do next.
VRR works really well already - some Nvidia users might lose extra functionality like Reflex Ultra that, when paired with VRR, can smartly adjust the frame rate cap. But VRR itself works.
HDR is a difficult beast though... It's hard even on Windows, and very problematic on Linux (though with Gamescope, KDE Plasma and Wayland you can kinda use it already).
Pornhub's 2024 statistics show that almost 5% of traffic came from Linux devices. This number doesn't include PCs that are used purely for work (probably).
I was able to switch to Wayland with an Nvidia GPU this year with the update to plasma 6. I've only been a full-time Linux user for a year now, but gaming has gone smooth, my install has been stable and Nvidia drivers are better. Arch install with LUKS encryption was very smooth with my last install a month or so ago.