Ghost Recon breakpoint is not currently working out of the box, but with a small tweak, you can get this working perfectly fine.
If you try and run the game out of the box you will get the following error
The first thing you will need to do is head over to desktop mode, open your steam library and select Ghost Recon Breakpoint.
Go to settings->manage->browse local files
In the Battle Eye folder open the file BELauncher.ini in Kwrite
Edit the 64.exe line from BE to BE_vulkan, save it, and close the file.
Now switch back to game mode and launch the game in Vulkan mode and you will be able play the game just fine using the default Proton (no compatibility).
The first launch may take a couple of minutes so be patient.
Thanks to bgreene07 on Reddit for posting the fix originally