I could solve the problem. But there is a fault in Gamepass App!
I had to go to Windows store. Search for MS FS 2020. there was NO Update Button! Like in Gamepass no Update Button also!
But I could choose „Install on all my Devices“ haha and then an 1GB Installation comes up from the windows store app.
Then run MSFS2020 and there the VR Update startet…what a Crazy way…