@NanoRaptor Seems I am one of the few to have an over-the-top #backup policy without ever having lost everything (in fact, I was able to restore everything from backup several times, although only once out of necessity).
For a long time I did daily backups to a SCSI tape. These days my Macs back up to three separate Time Machine storages (one local USB disk, two Unix-based file servers), and in addition the important stuff is backed up twice via rsnapshot, once onsite, hourly, once off-site, daily. All the backup servers use ZFS, and I regularly check the backups.
The nextcloud database and data is backed up daily, but currently only in one place as it contains no data that is both unique and crucial.