What notifications am I seeing?

I'm feeling pretty dense here... but it seems like all my notifications in the Qualtrics community recently are random. For example, I'll get a notification that someone commented on a post I don't seem to have interacted with at all...no post from me, no star. I'm wondering if maybe I just viewed these posts at some point? It's making it kind of difficult to keep track of the threads that I'm actually interested in following.