Node uptime. See some peoples posts asking for support:Uptime of 7+ years of migrated vm's or pve nodes itself ? But anyway that's good luck with hw and prepared environment.
If that are node years you could be sure not running on same time further ...
Here for example 1264 days of node uptime running kernel 4.13 in 2023
https://forum.proxmox.com/threads/permission-denied-error-for-vzdump-command.130885/#post-574612