Aha! That explains it, when you press verify in Steam it deletes your installation:
If you were trying to reinstall MSFS from scratch, that would be what you would need to do. However because you have already verified the installation (and uninstalled and reinstalled it afterwards as well!), your MSFS Steam installation should be okay and you should be all set to reinstall the sim into D:\MSFS2020 without doing anything else
