Hello @OlaHaldorSV ,
I do not know how you can reset your cloud save, but I was wondering what would happen if you launch MSFS without internet and with your local save games (wgs folder) removed. Would it launch, since there is no way it should be able to retrieve cloud saves? If so what if you change some settings and save your game. In theory, if you come that far and restart MSFS with an internet connection, syncing you Xbox game settings should notice a conflict between your cloud and local save, hopefully overwriting your cloud save with the local non corrupt save.
This is just a guess/something to easily try (backup your local saves before trying), until this is hopefully fixed.