GloriousEggroll has released a new custom pre-release build of their Proton fork based on the latest Proton release.

Proton-5.9-GE-2-MF

Hi all, I'm marking this as another pre-release as we still have some audio issues with media foundation, and a few other pending issues, however we also have quite a few fixes:

-Fullscreen hack is disabled still for compatibility with MK11.
-Rawinput re-enabled
-Nier/sekiro winex11 patch re-enabled
-winevulkan patches re-enabled
-The weird Skyrim mouse reverse input issue was fixed in 5.10, so I've backported it.
-There is some heavy work being done on wined3d and dxgi, which causes some additional issues, so TOXIKK and Killer Instinct require wined3d to currently run properly. Protonfixes have been added to do that automatically, so those games both work with wined3d currently.
-There is also some heavy work being done on ntdll in 5.10+, which cause esync and fsync patchsets to not be compatible. Due to this, I'm currently working with 5.9 and backporting specific changes necessary to retain esync and fsync compatibility.
-A dxgi native override was also added in protonfixes so that Metal Gear Solid V: Phantom Pain now works
-A fix has been added for the RE3 credits crash - thanks vitorhnn!
-A fix has been added for the MK11 and Injustice 2 video color issue - thanks vitorhnn!
-A partial fix for websockets has been added for Sea of Thieves so that login now works, however it is currently crashing after login on 'Opening the Journal' - thanks ga2mer!
-5.10 media foundation patches have been backported
-Remi Bernon's free range memory allocation patches have been backported which increases performance in We Happy Few and some other games.
-Proton 5.0.8 changes backported
-DXVK updated
-vkd3d updated
-FAudio updated

Known issues:

-Fullscreen hack still disabled for the time being to retain compatiblity with MK11
-Path of Exile cannot switch to vulkan renderer when using RADV, but works with AMDVLK. This is something else tied to fullscreen hack, as patching in fullscreen hack allows it to switch. RADV currently has a lot of graphical glitches with PoE anyway, so for the time being AMDVLK is the better option to use.
-Soul Calibur VI still hangs at intro due to incomplete SAR work in media foundation
-Injustice 2 and MK11 cut scene audio is missing due to incomplete SAR work in media foundation
-Borderlands 3 Marcus intro on new game audio is distorted due to incomplete SAR work in media foundation, but is skippable.
-Seven still only plays intro audio, no video, and crashes after starting new game due to incomplete SAR work in media foundation.
-libffi6 is still needed for some rolling release distros such as arch
-As mentioned, due to work being done with wined3d, dxgi is in an odd state. If a game works in proton, but does not work in proton-ge, try adding WINEDLLOVERRIDES=dxgi=n %command% to the options. If it works, let me know and I can add a protonfixes override for it.

Currently I would say this should be ok to use for most games except Soul Calibur VI and Seven

Download Proton 5.9-GE-2-MF from GitHub
Installation Instructions