Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.48

Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-04 21:32, hash: rBcf0ba59e311b

At first start after rebooting my PC Blender is missing parts of the UI and the splash image.

Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]

Not sure how to reproduce this. Here it happens reproduceable after a reboot and starting Blender the first time. The second time starts up as it should.