Proton-EM enters the new year! (Sorry for taking so long)
Most likely this will be the (second) last release before Proton 11 rebase.
There will be another HDR testing version (soon) that won't need any environment variables to activate HDR in games (other than PROTON_ENABLE_WAYLAND) of course.

New Stuff:

• proton: Drop automatic HDR WSI for Nvidia. (Nvidia 595 released!)
• winewayland: Import upstream window layering
• winewayland: Fix Vk->char conversion truncating to 1 byte
• winewayland: Fix right shift virtual key
• winewayland: Fix freezing issues when querying the window icon.
• winewayland: Add a hack to fix modifier key release with alt and meta keys
• winewayland: Send both normal and raw relative mouse inputs to win32u
• winewayland: Fix instances where wglSwapBuffers would freeze with windows that haven't turned visible yet.
• winewayland: Implement server-side decorations
  • These should be mostly stable; the only issue I have seen is windows getting stuck in split-screen mode, for example. You can just resize the window instead of trying to move it out of the tiled modes.
  • Unfortunately, the feature cannot be enabled by default due to compositor bugs. Popup menus are cut off on KWin. The test application I was using (winecfg) managed to completely break Hyprland, so I couldn't do any testing there. On Cosmic, the menus are cut off with CSD and SSD both 😆
  • If you want to use it, set WAYLANDDRV_SSD=1
• winewayland: Fix crashes with rectangular window icons (https://gitlab.winehq.org/wine/wine/-/merge_requests/10002)
• winewayland: Enable IME support and import fix for the key repeat issue (https://gitlab.winehq.org/wine/wine/-/merge_requests/10007)
• ntdll: Import Genshin Impact freezing on exit fix: (https://gitlab.winehq.org/wine/wine/-/merge_requests/9890)
• ntdll: An attempt to fix https://bugs.winehq.org/show_bug.cgi?id=59333
• Import upstream proton changes
  • FSR4 Redstone is now fully supported. Denoiser (Doesn't work on RDNA3 yet), Upscaling, MLFG, NRC :D

Winewayland driver requirements:

Compositor behavior varies a lot; from my testing, KWin is the best in terms of features and compatibility.
Nvidia 580+
Mesa 25+ (only because DXVK requires this)
Known issues with Nvidia:

• potentially increased input lag (compared to a pure x11 session, not xwayland)
  • We now have measurements: https://davidjusto.com/articles/m2p-latency/
  • Only XWayland is affected on Nvidia according to this person's numbers. edit: after an informal discussion with another person they said their measurements agree
  • According to older testing by a KWin developer (https://zamundaaa.github.io/wayland/2021/12/14/about-gaming-on-wayland.html) AMD GPU doesn't have any input lag difference (which makes sense since I don't really see why XWayland should affect latency in any way)
• 570 driver (and potentially lower) just freeze
  • Yes, it actually took Nvidia until May 2025 to get their driver working properly with wayland applications O_o

Winewayland HDR recommended configuration:

DE: Plasma 6.6+, works most of the time: Plasma 6.5, Gnome 48+
Drivers: Mesa 25.2 or greater, Nvidia 595+

Notes:

Please report issues in the issues section of this GitHub repository (Make sure it is specific to these builds and is not present on upstream Proton). I am open to issues related to winewayland as I'm the one working on it. However, if it is related to winewayland ensure that you test on winex11 first to make sure it is NOT an issue there. Ensure you put the same information that you would put in a normal Proton compatibility report (e.g logs, OS information). With winewayland issues, please mention your compositor and its version.

Please Read:

Read the docs to see all (new) environment variable options with this build: https://github.com/Etaash-mathamsetty/Proton/blob/em-10/docs/EM-ADDITIONS.md

Detailed summary of changes to winewayland: https://github.com/Etaash-mathamsetty/Proton/blob/em-10/docs/CHANGES.md

Well, you don't have to read the second one if you don't want to :)