[BUG] SteamVR green graphical snow after GPU replacement (Linux, Radeon RX 5500 XT)

The issue names no repository files, tests, or code entry points. Start by reproducing the green graphical snow on SteamVR 1.17.15 with the listed Radeon, Ubuntu, and Mesa versions, then compare the affected dashboard, desktop-view, and composited-window paths. Done means those VR elements and composited applications render without static or flickering artifacts.

Describe the bug
After replacing my GeForce 1060 with a Radeon RX 5500 XT, SteamVR now shows graphical glitches and some features no longer work entirely.

In several places, SteamVR shows flickering green static/snow. It is not consistent between eyes, the snow is different in both. In some cases, this is moving, dynamic snow. In others, it's a static image. A screenshot is attached of the static version. When in a VR application with no compositing/overlays, the static disappears completely.

The glitches appear in the following places:

• When in the dashboard/menu (dynamic flickering green squares)
• In the SteamVR default scene/dome, when looking at any component like the chaperone or controllers. (dynamic flickering green squares)
• xrdesktop has green static rather than the complete rendering failure of overlaid windows.
• Trying to view the desktop from inside the Dashboard. Screenshot attached. Note, this did actually used to work. (Static glitch)
• Windows composited into the scene, like the overlays used for streaming. (Static glitch)

None of this happened on the NVidia card; it happened when I swapped over to the Radeon.

To Reproduce
Launch SteamVR. This is the only required step to reproduce, as it happens instantly on load.

Expected behavior
No static around VR elements, and composited applications/windows to display.

System Information (please complete the following information):

• Distribution: Ubuntu 21.04 (Also tested and occurs in 20.10 and 20.04)
• SteamVR version: 1.17.15
• Steam client version: June 7, 2021
• Opted into Steam client beta?: Yes
• Graphics driver version: Mesa 21.2.0-devel (git-c04f20e 2021-06-08 hirsute-oibaf-ppa)
• Gist for SteamVR System Information: https://gist.github.com/ajrabassa/1fc2bf24511bef92116c25d9f5d7af2b

Screenshots

Additional context
When this occurred, I installed the nightly update PPA for Mesa and Vulkan drivers, so all packages related to Mesa are likely up to date. I also installed the Radeon performance tuning app and set it to high, as a comment thread suggested. This did help overall graphical performance, but had zero effect on the green snow.

Note: Commenters who are also experiencing this issue are encouraged to include the "System Information" section in their replies.