PeerTube federation issue (can't follow channels)

Hey there!

I’ve run into an issue with federation of my PeerTube instance (https://peertube.art3mis.de) which I’ve probably caused myself. I noticed that I couldn’t follow my channels on the instance from Mastodon, I got a webfinger error 422 (I think). I was unable to figure it out, but then I remembered that I used to have the instance run on a different server before I moved it to the current system. As I only had used it for testing then, I did not migrate the server, but rather installed it fresh under the same domain name (different machine though). I assume that’s why in the fediverse the server is already known but probably does use a different key or ID now than when I set it up initially. Might this be the reason I can’t follow? And if so, what can I do to fix this? Do I have to rename the instance, i.e. change the domain? Any hints would be appreciated. Thanks!