Transaction isolation level of nextcloud database

I am trying to install Nextcloud using a remote MariaDB server which is already hosting several databases. This server has transaction isolation level to default (which is “Repeatable read”) but Nextcloud needs it to be “read commited”. Is there any way to resolve this? Do I have to install a new database server? May I use the “read commited” level only for Nextcloud sessions?
Thanks in advance

Why can you not use the MariaDB on “localhost”?

Of course I could install a new MariaDB server on localhost, but I want to leverage the MariaDB server that I already have. It is a well balanced Master-Slave cluster with configured backups, and I would prefer not to have a database server for every single service I install.

Afaik we already set the transaction level for the session on connect:

I didn’t know it was the default behaviour. Thank you!