… it’s because MariaDB 10.6 doesn’t currently work with Nextcloud: MariaDB 10.6: Row format compressed is read only · Issue #25436 · nextcloud/server · GitHub
The installation of Nextcloud will print something like Row format compressed is read only.
You can install 10.5 explicitly to work around the issue for the time being. See https://github.com/nextcloud/mail/pull/5330 for reference.
Cheers