Per user encryption

There are three ways of encryption: https://help.nextcloud.com/t/per-user-encryption/42556/3

https://docs.nextcloud.com/server/16/admin_manual/configuration_files/encryption_configuration.html

All variants have some drawbacks in usability.

Share owners may need to re-share files after encryption is enabled; users trying to access the share will see a message advising them to ask the share owner to re-share the file with them.

After all, users need to trust the sysadmins of their hoster ;-)