Apologies for not replying earlier. I can't provide it anymore since I wiped my old proxmox installation and to 'mitigate' the issue I just named my new storage local-zfs even though it's lvm.
But it could be related to cloud-init as my images were using it as well.
I'm just trying out vzdump & qmrestore backups between different hosts. (backup host: proxmox 5.4, restore host: 6.0)
I've dumped a vm backup on one host, copied log & lzo files to a directory on the other host and when trying to issue restore command I get: