Trace dump suggests that crash occurs while executing cpuidle
module.
Try to boot with "intel_pstate=force" kernel parameter [1] to force
different CPU driver (if CPU supports it) and\or "cpuidle.off=1" to
disable cpuidle subsystem.
Thank you Alexander and Georgi (thanks for the link!) for your answers. highly appreciate it!
I have tried the additional kernel parameters intel_pstate=force and cpuidle.off=1 but unfortunately this didn't solve the problem. The freeze still happened at around 50% of the boots.
I now wiped Bullseye and installed Buster. The very same server was rebooted at least 10 times without any hiccup/freeze/crash.
Or if they are Kernel related (Buster uses 4.19, Bullseye 5.10) it might be a completely different problem.