@greygoo
No, that's another Fediverse software in development. Who accidently federated due a test and get measured by fedi.db.

@Gargron

@greygoo @Gargron nop, not really. That is single server that had create 30 million actors (users) for test purposes, but they didn't actually do anything. It wasn't supposed to federate, but was an accident.
If that was the source of the spam, one could just have blocked this single server.

The spam wave is some script kiddy going around and searching for servers with open registrations, and registering accounts there using disposable emails. These accounts then start tagging people with spam.