When will the next stable release of CB be?
No idea, but likely won't be for awhile. So at the very least a month.
We need time to adjust, since all our servers are on Debian Buster that comes with MariaDB 10.1 and Bullseye doesn't even have a release date yet.
You only need the minimum version, which is MariaDB 10.2.7 which came out in 2017 and should be available everywhere by now. The recommended is always going to recommend latest release and is up to you if you want to use the recommended.