Older installation? Asking because we're only defaulting to pinning network interface names to the mac address of the interface since the PVE 9.0 ISO installer and the new kernel might have cause a rename of the interface name as per systemd/udev default policy.
You could check the system log of the previous boot to confirm that, e.g.
journalctl -b-1 (or web UI -> Node -> System Log)
If that was indeed the root cause, you can use our the pve-network-interface-pinning tool once to pin the network interface names to avoid this from happening again, see:
https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#network_override_device_names
If not, see if there is an actual error in the system log from the previous boot.