>>dredmo+(OP)
Is a federated system like Mastodon not setup in a way that users have access lists and if one server is down they simply connect to the next? I would expect to just limit the access to my server in a way that no illegal content is added to its storage and I don't have to pay horrendous fees for the network traffic and then just let the DDOS happen. At some point it needs to stop since the DDOSer will find nicer targets and the source of your problem will not have enough funds left. And then your service simply continues.
That's at least how I think a federated system should work. Not sure if reality matches that.