More info here:
Update 10/19/2021: And it keeps getting worse, but at least it's bright and sunny in the reality where Thingiverse seems to reside. Unbelievable that they don't even care enough to add any notice to their main page to notify users, many of whom may be using the same user and passwords across multiple sites, and now are in danger of real problems. There won't be any consequences in this country for the way they have handled this I'm sure, but maybe the laws in the EU will at least get them to make the proper notification and come clean about what was taken.
I have been trying out some alternatives to Thingiverse and the latest problems have only accelerated things. The best alternatives I have seen so far are Cults3D and PrusaPrinters. Neither are perfect and their communities seem to be less active, so I will probably be (unfortunately) sticking with Thingiverse as a primary location for files. Cults3D allows selling of files (which is not currently something I care too much about), and Prusa has contests (including one I have entered some designs into) and seems to have a much more engaged management. Both the sites mentioned will automatically download designs from my Thingiverse account which makes it very easy to migrate. I did not copy everything over however, since many of my things are remixes and I need to make sure they are pointing back to the original sources. Anything I have that is original though, should be up on Prusa and Cults3D.