Yes, something similar happened to me too. In fact, It's been happening for some time. The ones where there is more engagement, too seem to make less money compared to others. I guess the algorithm doesn't understand quality and they also get a bit crazy about fair delegation of money across articles based on their engagement. One thing I can imagine is that it depends on what kind of readers read your article, how long they stayed on your article(even if it counted as a read), and some secret formula which we will never understand.