> I have a dedicated server running my email and media server where I also put a `ghcr.io/linuxserver/quassel-core` docker container, and it doesn't consume anything

It's still consuming your time and energy and that's a running cost by itself. I'm also a long-time Quassel user in addition to be a long-time IRC user, but I have no more energy to manage my own Quassel server and my current instance has been long neglected.