I think a lot of people also buy MSFS directly from the Microsoft Store on PC. For X-Box, they can only buy MSFS through the Microsoft Store, Steam isn’t even an option on X-Box.
I know that back in September, Laminar Research was forcing XP 12 advertisements on XP 11 users, after XP 11 users had spawned into the airport. Some XP 11 users were also calling those XP 12 advertisements “spam”: How to disable this advertisement from LR in X-plane 11? - General X-Plane Discussion - X-Plane.Org Forum.
Then you have the 33% sale of XP 12 only 4 months after it was released. If you ask me, that is signs of desperation. Like real desperation. XP 12 sales must have been that bad.