Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 660 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 445.87
Broken: version: 2.90.0 Beta, branch: master, commit date: 2020-08-05 21:36, hash: rBc5b6b3d82f56
Short description of error
After I move two parallel flat shapes, they shows wrong overlap. Glitch disappeared after I refreshed stroke (on-off).
Steps to reproduce.
Select and delete all.
Top ortho view.
Add blank GP
Draw mode, draw a circle.
Disable stroke, enable fill, color it white.
Perspective view, angle about 45° from up
Duplicate circle Z, scale it down
Make material unique
Move down second circle with GZ under first one.