I don't know, but from a programming point of view, I would assume that the algorithm for selecting recommended questions is based on their relevance to the question (s) you are browsing. They aren't necessarily linked to the user's activity. Makes sense?
I haven't noticed this particular issue, but I've noticed something similar.
When I am suggested certain questions to open, there are lots of questions from "Anonymous" that I'm all but certain come from users I follow. It's kinda obvious in certain cases who writes those questions, weakening that user's ability to be anonymous.
It shouldn't happen if you have no anonymous opinions allowed if you ask anonymous questions anyone can answer them with no problem and they really need to stop that from happening and if you allow anonymous users to post their opinion yes it can happen that way too ,