Since I moved my installation to a small SSD that only holds the root partition, I thought not seeing the root disk in the GUI, and not being able to mess with it, would be a nice thing.
So I removed the sharerootfs-plugin because according to the description, I thought this was what it does. Well. This apparently removed the KVM, snapraid and compose plugins as well.
I was able to reinstall all of them and my configuration was still there, but I think it would be nice to include a warning in the future. I might not be the only one with this thought.