Using Manjaro kernel tool (manjaro-settings-manager → Kernel) and/or mhwd-kernel, I upgraded to Linux 6.1.23-1. After this, and perhaps some other package updates/installed including virt-manager, all devices connected to my AMD GPU started showing a blank screen. TTYs worked, but in the GUI/Xorg just a frozen screen, usually just a blank screen with an frozen/unchanging cursor.
My system has NVIDIA TU116 [GeForce GTX 1650 SUPER] and AMD Cezanne [Radeon Vega Series / Radeon Mobile Series]. Via the mhwd / manjaro-settings-manager → Hardware Configuration, I had always had selected video-hybrid-amd-nvidia-prime, proprietary drivers.
After much searching, turned out the problem was that the file at /etc/X11/xorg.conf.d/90-mhwd.conf had no configuration lines in it and placing the following after the comments solved the issue:
Option “PrimaryGPU” “true”
Option “OutputClass” “amdgpu-pro”
I’m not sure if it’s a bug in the new packages, or some quirky circumstance that occurred in my system, but in case others encounter this as a common bug, I post this here for reference.
Perhaps similar to some other posts: Grey screen then blank when trying to use display port and hdmi port on GPU, External monitor won't work, Laptop monitor detected but not working. External monitor detected and working,