This post by @DePemig was eye openning for me: "Mutuals are not friends".
https://blog.gillesdutilh.com/2026/05/mutuals-are-not-friends/
I had naively assumed that if two accounts followed each others they were obviously "friends". This isn't true! Friendica and Facebook have a Friends layer *above* mutual following. This provides more #UX options allowing you greater filtering and interaction options.