@laprice following/followers on kolektiva is public by default and available un logged in so that is trivial to scrape without notice. you can view that all from Tor easily. I guess its not already in a nice database format but that vector doesn't seen much different.
@liaizon having it all in one place enriched with the network of dm contacts would be slightly better than public information. But they probably have all of that through packet tracing anyway.
The longer term threat is that those connections are now recorded in their profiling graph and are available to machine learning efforts and usable by agents with bad agendas. (I.e. Arab teens that they groom into activists for counterterrorism clout)