Of course, we always use one of the latest versions of MySQL / MariaDB or PostgreSQL on our servers. If your server with us still has an older version, then it may be that your database would not work with one of the newer versions and we have therefore refrained from an update.
For web hosting packages we do not use the latest version, but stay a few versions behind - as long as there are no acute security holes. Usually with new versions come not only new features and bug fixes, but also new bugs.