I’ve noticed this in Japanese, which is the only hard language I study now. The last few months, each of the 10-point exercises start with something easy, and then gradually ramp up with the last questions generally being the hardest. Until then, there was a long time when you could randomly get only beginner exercises or only advanced ones. Now you get a bit of each, each time, even though there is still some random variation in just how hard they get.
This change makes difficult languages less intimidating, as I know I won’t get stuck on an exercise that will take long time and be very frustrating. Even so, I am not really making progress on Japanese, just keeping it warm, while I get distracted by other shiny things. Like Latin, which just came out in beta. But that is a story for another day, if ever.