Just some general thoughts, hopefully helpful in some way:
Userspace code can never (directly) cause a real freeze, it is either hardware or kernel/driver.
Almost always if a system appears frozen, it can still do more than most people assume:
- try to ping the system
- try to ssh into the system
If successful, kill/restart possibly offending processes or do a “reboot”
- try Alt+SysReq+R,E,I,S,U,B
This is the lowest possible access to the kernel
I don’t have a Librem, but i assume you have to press Fn+PrtSc for SysRequest and release it after each letter
Or, just use an external keyboard
It would be interesting to know if the result is the same fore everybody affected.
On the video decoding:
This might only create reproducible results if everybody decodes the same file, or at least the same encoding, maybe resolution etc. If hardware decoding on the GPU is involved, your screen may be dead, but ssh could still work. Then, a kernel (GPU driver) update could be the cause.
But even if “only” the GPU is stuck, I could (hardly, but still) imagine that some hardware problem is at the root, like the voltage regulator can’t handle high GPU usage plus CPU freq changes at the same time. This, in turn, could have been hidden with an older (less optimized?) kernel.