@65dBnoise "Friends of Friends" and "Similar to Recently Followed" personalized_suggestion
The former seems self-explanatory.
The latter requires a bit more Mastodon knowledge than I have. I think it uses the "More Like This" feature of Elasticsearch, looking for non-bot accounts "similar" to ones you've followed, with a boost to domain-verified accounts? I *think* it's comparing text from the profile, might be wrong. https://github.com/mastodon/mastodon/blob/c07028b2fae4dc692570df84227023ca90443288/app/models/account_suggestions/similar_profiles_source.rb