I have been having graphics/display issues when using latest Qubes OS release on a Librebooted T480 Thinkpad.
The issue:
After logging in to QubesOS for a period of time specific type of graphic glitch occurs, which is a red/blue/purplish line across the display moving up from the bottom of the display. This is usually followed by a black screen (but not always). A reboot is then required.
The issue cannot be replicated when running any of the latest major Linux distros (Debian, Fedora, Ubuntu, Kicksecure, Kali, Parrot etc) on the same hardware and stress testing the Intel CPU/GPU in just about every possible way. The issue only occurs when using Qubes.
TODO:
When I have time I will flash back to stock Lenovo BIOS and repeat the same tests.