We want to move to puppetdb 7 and initially run it on Bookworm. This will still see quite a bit of changes given it's not frozen yet, but backporting puppetdb 7 to the Clojure stack in Bullseye is also a significant undertaking (and this way we can also help with getting puppetdb in shape in Debian).
The Debian installer isn't yet adapted to install Bookworm in our infra, so initially a bullseye node will be dist-upgraded (and minimal puppet changes deployed to support the core base classes).