I prefer the current behaviour.

It’s easy to open a link in a new tab without right clicking. You can middle click (Windows and Linux) or command+click (MacOS). However there’s no easy way to force a browser to open a link in the current tab if the site wants to use a new tab.

I’m not really sure that a K/V service is a more scalable option than Postgres for storing text posts and the like. If you’re not performing complex queries or requiring microsecond latencies then Postgres doesn’t require that much compute or memory.

People can get unnecessary scared of relational databases if they’ve had bad experiences with databases that are used poorly, but attempting to force relational data into a K/V can lead to the application layer essentially just doing a less efficient job of the same types of queries that the database would normally handle. Maybe there’ll be some future need to offload post and comment bodies into object storage or something but that seems incredibly premature.

Object storage for pictrs is definitely a fantastic addition, though.

Expecting communities related to a certain topic to coalesce on a single server doesn’t seem like a good idea to me, but having some kind of community metadata would definitely be nice. As you said it’d be useful as a way to filtering out certain topics, and it might also be handy for community discovery.