I would like to add new nodes to my cluster. Is it possible to add Proxmox 7 nodes with the latest ceph to my Proxmox 6 ceph Nautilus cluster? Or should I upgrade first?
It is not recommended to run a PVE cluster with mixed versions. As PVE 7 uses Ceph Octopus/Pacific, this might create even more problems.
According to the documentation, your best course of action would be to upgrade your Ceph versions, then upgrade your nodes. After that you should make sure that your cluster is running healthily, then add the new nodes.