as so many others now i ran into the same bug, where opening the sim sends me to the MSStore to install gaming service which obviously is allready installed.
Before that, the game crashed after being away from the pc, after trying to restart i got this error. however as i was checking if either gaming service had an update or anything changed in the mendatory C: drive folder i realised that the icon changed from a “folder” to a “folder-shortcut” and the folder was completely empty, so i prompted the sim in the MSStore to “install on this pc” which downloaded the rughly 1gb to the C: drive and i could just start the game as usual.
can someone ( @spatialprof ?) still with this issue check if the folder (MSStore version) C:\Program Files\WindowsApps\Microsoft.FlightSimulator_1.20.6.0_x64__8wekyb3d8bbwe
is indeed only a empty folder-shortcut?