We've made changes to our minimum system requirements as announced below.
www.joomlapolis.com/blog/kyle/18944-minimum-system-requirements-update
You should not need to update your database anymore. We're decided to just use Joomla 4 minimum database requirements, which are as follows.
MySQL 5.6
MariaDB 10.1
We do not have a time frame for CB 2.7, but shouldn't be too far off once we've all the J4 compatibility issues addressed.