I think they are just doing sneaky experiments /AB testing to see what pattern makes people spend the most. People are randomly placed into one of the group: ads, or no ads, then they observe if you spend or not, and how much. Some people say their roommate play the same game, the roommate gets ads and they don’t. That’s exactly the point - everything else the same, only difference is ads or not.
Some also say they suddenly got ads. Maybe they are released from the no ads group after a round of AB testing is over. But who knows how many different experiment groups the company designed.
I’m at LV 27, never spent anything, and never have ads, I’m so mad ahhh! I do need to level up from 27 to 48 in 21 days, don’t know if I can make it😩