MSFS has some “interesting”, (as in Chinese “interesting”), quirks - and like the Minoan maze, there is the occasional Centaur in there. People discover them all the time, (you can consider them “Easter Eggs” if you wish). So much so there is an entire forum dedicated to them. 
https://forums.flightsimulator.com/t/what-annoying-msfs-bug-flaw-still-remains-in-2023/567370 - among others
It should be noted that a “splash screen” displayed while loading is a very common Windows program behavior - even X-Plane (11 and 12) do this, but they don’t display a screen that could be confused for a request to update.