Thanks Dick for reporting #1006388! We need to fix multi-arch support on MariaDB 10.6 in unstable before we can consider backporting anything to Bullseye/10.5. Right now we don't have anybody on the maintainer team who fully understands the Debian multi-arch stuff.
If you have suggestions on how to update the debian/control file to have correct Multi-Arch stanzas, please submit a Merge Request. https://salsa.debian.org/mariadb-team/mariadb-server/-/wikis/Contributing-to-MariaDB-packaging-in-Debian
