What caused this boot?

Ignoring time inconsistencies - nothing interesting. Your guess is as good anyone else's:
power loss, bad memory, bad cpu, bad pci bus, zero day kernel bug...

Keep digging in your logs or use one of the web articles to improve your system data collection on crash.
Not all things in life can be explained.


Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox