Valve has today released the newest version 5.0-5 of Proton with the following changes:

5.0-5:

Fix crash in some games introduced in Proton 5.0-4.
Fix networking error in Granblue Fantasy: Versus.
Support for latest OpenVR SDKs.
Add support for new Vulkan extensions used by some recent titles.

Not even one week after the release of Proton 5.0, Valve already presents the first update to it:

5.0-2:

Fix frequent crash introduced in Proton 5.0-1 related to video and audio playback.
Fix Planet Coaster crash on launch.
Fix Subnautica graphical issue.

Today Valve released the next major version of Proton: Proton 5.0.

You can install it manually by using the command

steam steam://install/1245040

You can also install it via the library in the Steam Client (in the Tools section).

Proton 5.0-1

Valve has released the Version 4.2.8 of Proton in the Steam Client for Linux:

4.2-8:

You are already using Proton (aka SteamPlay)?

In this new forum post I'm gathering some useful tools and links around this topic!

The list is going to be extended in the future - so please let me know, if you find anything. :-)