I have rendering artifacts in Enter the Gungeon with RadeonSI.
Bug was reproduced on both a Radeon 7 and an RX590 using Mesa git versions
The game rendering is fairly simple and may not be too hard to track down.
The rendering artifact is the shimmering around texture edges in the video I will provide.
I've also attached a renderdoc capture of a frame in the game where the artifacting is occurring.
Additionally the game is running very slowly due to massive amounts of futex usages, but I can trace back if those are coming game side or driver side.
RenderDoc capture: https://drive.google.com/file/d/1P1Dr2g4L8LpC7CBfVmriWX8X7F-mLx0w/view?usp=sharing
Some additional information.
If you change their lighting model from High to Low in the video settings then the corruption goes away, but this is obviously less than ideal.
Definitely something to do with that shading pass though.
I don't seem to suffer with poor performance even on an obsolete Phenom II x4 955. But now that you've mentioned when I notice a very slight bit of this shimmering effect on my R9 285, admittedly not to the same degree as you.
It's quite noticeable on the first red step at the beginning of the game and seems to shift around with the position of the game camera:
Using the GOG v2.1.5 release on:
> Debian Testing
> Mesa 19.1.0-devel (git-53f715fafb)
> Device: AMD Radeon R9 200 Series (TONGA, DRM 3.30.0, 5.1.0-rc1+, LLVM 8.0.0)
Recorded a trace running the x86 & x86_64 build of the game: