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.
Isn't this what all you lemmy-worlders got mad at Beehaw for doing? I don't think it's unreasonable to ask for a small statement from people as an anti-spam measure (a sort of advanced captcha), though of course the big problem there is reviewing all the applications in a timely manner. Still, I think there's room for more and less exclusive instances. The tools are there for instance owners to protect their instances however they choose.
Beehaw got their knickers in a twist because of some spammers, back when lemmy.world and shitjustworks had... maybe 30,000 registered users in total. The solution there was adding more moderators. You don't chop your leg off because you got a few papercuts.
If you look at the volume of bots (some instances went from hundreds of users to >12,000 overnight), that's potential for worry. There's ~500,000 bot accounts sitting out there waiting to be activated. No amount of moderators can block that fast enough, and that's when de-federation should be considered.