Trying to move over a following list and I noticed some things.
- the UI of Mastodon indicates 4 failures. There were 9.
- The import seems to not be able to follow GoToSocial instances.
- There's an account I can't follow, that is also not moderated away. I only noticed the instance URL being similar to a banned instance URL, but the instance URL itself is not banned.
Anyway, time for more research, I guess.