I don't believe this is possible with our current RAID settings.
At this point I'm considering if we should stop looking for the root cause and instead think about workarounds.
Could we perhaps create an automatic mount job for the efi disk after boot?
Ok. It is still a bit concerning. You don't actually need to mount the EFI disk at boot, proxmox-boot-tool will mount it automatically during a system upgrade if it is necessary, so you can just remove the entry from you fstab entirely.
