I've just posted a quick blog post explaining why all Mastodon people should be very concerned about "Mask Group" having bought up 3 of the largest mastodon instances, and why folks on those instances should be moving their accounts ASAP.
tl;dr there's no logical reason to buy them that doesn't hurt them and us in the long run.
https://weblog.masukomi.org/2022/12/21/mastodon-ownership/
thanks to @stux for pointing this out.