Hello Otto, Thanks for an invitation. Definitely, will do next time.
This bug has been fixed by upstream (https://github.com/MariaDB/server/commit/4ad148b148cfbb6f78b33ad9a7662f47c24cb759) and already entered into unstable (https://salsa.debian.org/mariadb-team/mariadb-10.5/-/commit/f161bfff73802d1c44510b54c83b09daa2c9a6a1). Furthermore, the branch "bullseye" is also up-to-date with the new upstream version. I'm not sure how to proceed in such situation...