Blocking instances for potentially suspicious activity

It's no secret the bots have arrived on Lemmy.

I've been monitoring https://fedidb.org/software/lemmy and it seems that a number of instances with open sign-ups are getting thousands of new user registrations but have very, very little user activity to show for it.

To stay ahead of potential problems, I'm preemptively defederating several instances that appear to be used for bot signups. If there are instances that contain legitimate content that end up blocked I will be more than happy to consider removing them off of the list. The intent is not to remove access to legitimate content, the intent is to make it more difficult for bad actors to propagate spam to communities hosted here.

Current criteria I'm looking at:

• Little/No mention of the instance on popular social media sites -- I don't want to defederate an instance that became popular overnight for legitimate reasons
• Large number of accounts (>5000)
• Very little local posts/comments (<25)
• Few/No subscribed communities elsewhere (<5)
• Very low active user count in the past day/week (<20)