Krist0fh back on August 15, you made a post enquiring about exactly this question:
Are you sure if buying the upgrade are we getting the full game. Some people says that when the game pass ends you have to buy the standard edition to keep playing. But I didn’t found any official word about this.
https://forums.flightsimulator.com/t/xbox-pc-game-pass-fs-upgrade-bundles/142830/3?u=thatajwguy
The responses to your question made it clear that the upgrade didn’t include the base game.