Operating system: Linux Mint 20 with XFCE - 64 BIT
Graphics card: AMD ARUBA (DRM 2.50.0 / 5.4.0-48-generic, LLVM 10.0.0)
Broken: 2.91.0 Alpha, branch: master, commit date: 2020-09-28 19:10, hash: d5353eea5b28
Worked: Blender 2.90.1
Short description of error
Exact steps for others to reproduce the error
Based on the default startup. A graphic glitch appears in all boxes. It is as if the boxes were "triangulated", with the triangle at the bottom that is highlighted when the mouse is moved over.