On the note of fake followers, before I blocked gab.com on our https://m.abunchtell.com instance I noticed very bot-like behavior from seemingly real accounts on that instance -- very reminiscent of birdsite bots.
Definitely worth thinking about how we guard against misinformation and astroturfing in the #fediverse as this gets more prevalent. Domain blocks alone probably won't be enough -- the classic social media features we include or leave out matter, too.