Quite a while ago I migrated my Mastodon container from Debian Buster to Debian Bullseye - but without migrating the PostgreSQL database from version 11 to version 13. There were more important issues on my list, and a migration seemed tricky at first - especially with a relatively large amount of data for my circumstances of 80 GB. The stability of my Mastodon instance was more important and an upgrade would only eat up unnecessary time and expose the instance to some downtime, which I initially wanted to avoid.