Nextcloud asked in a poll at https://mastodon.social/@nextcloud@mastodon.xyz/115095096413238457 what database its users are running. Interestingly one fifth replied they don’t know. Should people know better where their data is stored, or is it a good thing everything is running so smoothly people don’t need to know what their software stack is built upon?
I’d say 9/10 aren’t doing proper backups given most people don’t actually do DR runs and verify whether they can fully recover from their backups. If you don’t test your backups, you don’t have backups!
90% is a bit low if the requirement is a full backup of nextcloud with database that is easily restorable.
If they do backups, most just copy the important stuff manually to an external hard drive.