Dont install launcher on H drive or partition.
Install laucnher on C (2GB) packages and community on H.
For example
H:\MSFS 2020\Official\OneStore
H:\MSFS 2020\Community
So now create folder named MSFS 2020 on H.
Go to
H:\WpSystem\S-1-5-21-1957421520-3008539413-1889401979-1001\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages
- copy Official and Community folders
- paste into H → MSFS 2020
Important
Uninstall MSFS → YES, uninstall MSFS 
Restart PC.
Open Xbox app
Click My Library → Microsoft Flight Simulator
Install
Install MSFS launcher (2GB) on C
By default → C:\XboxGames
(…)
Launch MSFS
Once you reach the installation manager screen - click on the path bar (address bar).
Select the folder you created earlier H:\MSFS 2020
let the installation manager scan the existing files
Fly safe capt!