How did they do it
Wow, I really like nostr:npub126yeu6j4c9rhrfz63r9ep2qzvgaquvs3ag2ywpt79jv8z7tvu47qkx6r3n ! It improves the visibility of notes a lot.
Discussion
Spam
I don't know for sure, but probably by propagating reposts from one recommendation bot to another in a background layer or something like this. For example, I don't have to scroll through my feed like crazy to read notes that I missed during the day. Some of them just pop up in my feed automatically.