Tape restore Problem - TASK ERROR: unable to find media

PVE it says "Starting VM failed. See output above for more information. (500)"
this is probably a different problem. i'd check the log file in /var/log/proxmox-backup/file-restore/qemu.log (on the PVE node where the file-restore is initiated)

2023-07-05T13:09:45+02:00: All chunks are already present, skip phase 2...
this would indicate that all chunks already exist...

can you post your /etc/proxmox-backup/datastore.cfg?