Valve together with CodeWeavers continues to improve Proton, which is based on the experience of the Wine project and is aimed at ensuring the launch of Linux-based gaming applications created for Windows and presented in the Steam directory.
Proton includes the implementation of DirectX 9/10/11 (based on the combined projects D9VK and DXVK) and DirectX 12 (based on VKD3D), working through the translation of DirectX calls to the Vulkan API, provides improved support for game controllers and the ability to use full-screen mode regardless Screen resolutions supported in games. The project also includes many patches, such as WINEESYNC, FSYNC and others.
In this version of Proton, Direct3D 12 mode was supported in Metro Exodus, a crash when launching in The Walking Dead: Saints and Sinners and eFootball PES 2020 was fixed. Also, errors were fixed when loading some assets in Automobilista and mouse regression with a high polling speed .
See a list of changes made by Valve here.