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.
I think also a symmetric approach is understanding the economic incentive and attacking that. At the moment I did not understand yet why people would create bots for Lemmy, but whatever we can do to make it as expensive as possible to do so (computationally, economically) and therefore less profitable might be a solution to pursue.
A danger with the application for example is that I think will potentially DoS the instance registration for real users, if spammers pipe the registration to some LLM and then the admins will need to spend the time to discern automated/chatGPT applications from real ones.