I have the same issue with UE-84919 on Windows and I am also using 2 x Radeon 5700 XT (BIOS cross-flashed to Anniversary Edition).
I experience graphical corruption in the Viewport whenever I click anything inside the Unreal Editor. Linux doesn’t even run, with an “CommandLine Error: Option ‘help-list’ registered more than once!”
Happens with 4.25.1 as well. Using DX, no graphical issues. Assuming a Vulkan issue.
While spam-clicking the Unreal Editor, GPU memory goes up by about 100MB-200MB. GC seems to kick in shortly after stopping clicking and drops it back down.