Good morning.
Can you report back the outcome of the following commands?
# listing related database services
systemctl | grep mariadb
systemctl | grep mysqld
# checking status of new mariadb version used by nextcloud
systemctl status -l rh-mariadb105-mariadb@nextcloud.service
# list of databases on new mariadb instance
/opt/rh/rh-mariadb105/root/bin/mysqlshow --socket="/var/run/rh-mariadb105-mariadb/nextcloud-mysql.sock"
# list of databases on old mariadb instance
mysqlshow
# list of database users on new mariadb instance
/opt/rh/rh-mariadb105/root/bin/mysql --socket="/var/run/rh-mariadb105-mariadb/nextcloud-mysql.sock" -e 'SELECT user FROM mysql.user'
# list of database users on old mariadb instance
mysql -e 'SELECT user FROM mysql.user'