Some observations from me that may point to this being an OpenGL issue:

* Vulkan applications seem to work (mostly). I've not had a crash with the
Dolphin Emulator with the Vulkan backend and Heat Signature, a game that runs
through Proton. This doesn't explain Rise of the Tomb Raider though. I've also
had freezing issues with Overwatch via Lutris/DXVK.

* Running freezing games in windowed mode stops hangs. In CS:GO, Minecraft, and
Team Fortress 2, my system freezes in the menus. When I run them in windowed
mode, they seem to run fine

* OpenGL games freeze after mouse input (for example, selecting a menu item).
This is when CS:GO, TF2, and Minecraft freeze up. 

I am using Manjaro on kernel 5.4-rc4, mesa 19.2.1-2, vulkan-radeon (radv)
19.2.1-2 and xf86-video-amdgpu 19.1.0-1. I use KDE Plasma 5.17.1