can i updade nextcloud to a more recent version?
Nextcloud should be updated only by using the MiaB upgrade scripts. You will almost definitely break your MiaB installation if you don’t understand everything about how MiaB is installing and using Nextcloud, which means reading through the source code. People post on a somewhat regular basis with this and the other thing of unlocking the admin and this breaks MiaB and they don’t understand why or how to fix it and the most common response is “restore from most recent backup”.
and will MiaB get a more recent nextcloud version?
or remove nextcloud from MiaB to install another on the same server using docker.