I have been using redhat ES and centos at work for years and after watching some videos on being able to play games on linux now, I decided to take the leap.
Using V3.68-2 live usb I installed on my desktop and installed steam and games worked, so far so good.
Today I decided to update and changed out some web notes on yay and ran it as just "yay’ which I understood to be the same as “apt update”. This installed a few packages including an update nvidia driver (535.113.01-2 → 545.29.02-2).
After rebooting the system looked normal until I logged in, then anytime I move the mouse the screen goes blank. This makes doing anything very difficult.
Using the live usb I can mount the root filesystem, and the pacman.log look OK on initial review.
Might be a bug in the latest Nvidia update. If so, a temporary help could be downgrading nvidia-dkms (and nvidia-utils) to the previous version, and hope a fix will come soon.
I managed to copy the output from that command but opening Firefox blanks the screen for about 59.5 seconds per minute, so it is not going to be possible to post it in the current running environment.
Ctrl+Alt+1 bring me to the kernel boot screen, but I get no visible cursor and enter does nothing, Ctrl+Alt+7 brings me back to the gui.
This forum has had a few threads about Ryzen issues. Sometimes the kernel updates have helped. A new kernel is coming soon, so there’s hope.
In the meantime, as mentioned above, you could try temporarily downgrading those Nvidia packages (and reboot) to see if that helps.
Also, if there are motherboard firmware updates available, that might help.
As I don’t have AMD CPU on any machine, help from my side is limited. But there are others here with such CPU, and surely they can provide better insight.