I'd like to see easier upgrades between major versions, or at least published docker images that can do the upgrade. As it stands, it's a huge hassle to get both binaries installed on the same system. This is a task almost everyone has to do periodically, it should be easier.
I also found it strange that PostgreSQL cannot simply support data formats of previous versions. In contrast, the latest version of ClickHouse[1] (23.1) can be installed over the version from 2016, and it does not require format conversions or any other migration procedures.