It seems like some FOSS websites started using a Proof of Work CAPTCHA called Anubis because they've been getting hit by crawlers to gather data for LLMs. It seems like it helps.

It does not stop them, but it does make it more expensive and slower for the attacker. At the moment, I haven't seen any instance having this problem, but it most likely will be a problem someday and being praped for it is definitely not a bad thing.

Lemmy could benefit from this by maybe placing some invisible or auto PoW CAPTCHAs when doing some action like commenting, posting, etc.