On February 15th, newly-created Fediverse accounts started posting spam messages from various instances, sending invites to a Discord server for a Japanese troll organization. This spam was widespread across the Fediverse. The posts frame ap12 from “KuronekoServer” as the culprit behind the operation.
Looking at their spam content (in Japanese)
I don’t think really anything, it just takes more effort and they’d need to change the domain every time they get blocked. I have seen a few services hosted solely for spam and bad faith practices, though they were Mastodon, Plemora, and Kbin servers, not Lemmy.