Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.89
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-02-21 00:52, hash: rB4dd782a1a395
Short description of error
The fill direction buttons in the Brush settings panel are vertical aligned. This looks odd. And is the only toggle that i have found so far that is vertical aligned. So i would classify it as a layout bug.
Exact steps for others to reproduce the error
Add a Grease Pencil object
Switch to Draw mode
Turn on the Fill tool
Have a look at the Brush Settings panel in the sidebar.