Please. Captcha by default. Email domain filters. Auto-block federation from servers that don't respect. By default. Urgent.
And yes, to refute some comments, this publication is being upvoted by bots. A single computer was needed, not "thousands of dollars" spent.
That's just a software / moderation issue though right? If as an instance owner you see a request from someone at "notaspammer.lemonparty.net" but six other subdomains have already been banned from "lemonparty.net" then you'd probably be pretty unlikely to approve any application.