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?
Will Nextcloud run apps not marked as compatible with that version?
No.
Bugs still happen. Just did with the most recent version and the polls app and mysql
You can specify the behavior in a few places, gui, occ command, config.php. By default no, but if you have an app you want to force in regardless of the version compatibility you can make it so https://help.nextcloud.com/t/help-what-is-app-install-overwrite-for/71523