From what I read, it was originally higher (82%), but went down because SteamOS has X11 as its default.
You can read more about KDE X11 plan on here: https://pointieststick.com/2025/06/21/about-plasmas-x11-session/
Quoted from the blog: "Current status: Plasma’s X11 session continues to be maintained.
Specifically, that means:
- We’ll make sure Plasma continues to compile and deploy on X11.
- Bug reports about the Plasma X11 session being horribly broken (for example, you can’t log in) will be fixed.
- Very bad X11-specific regressions will probably be fixed eventually.
- Less-bad X11-specific bugs will probably not be fixed unless someone pays for it.
- X11-specific features will definitely not be implemented unless someone pays for it. "