Yes, this is the most likely cause, in my mind.
There have been numerous posts by people since 24.10.X running older Ryzens specifically complaining about “random reboots when idle”, a key symptom of the older Ryzen power issue at idle.
Update the BIOS and set Power Supply Idle Control to Typical.
I wouldn’t change the other settings. The above should resolve the crashes.
Changing PBO, CPB and so on are likely red herrings.