upgrade from 7 to 8

Hello all, I'm running multiple 3-node clusters, installed Proxmox VE on top of a plain Debian Bullseye (without using the Proxmox VE ISO) on version 7.4-16 with a no-subscription repository and recently I've proceeded and successfully upgrade one 3-node (lab/test) PVE cluster to 8.0.3...

When running the pve7to8 checklist script I get this warning: "WARN: Found at least one CT (157) which does not support running in a unified cgroup v2 layout. Consider upgrading the Containers distro or set systemd.unified_cgroup_hierarchy=0 in the Proxmox VE hosts' kernel cmdline! Skipping...