My G2 is new (3 weeks). During my first few weeks I experienced the same set of issues you are describing.
I finally realized that whenever or however I tried to ‘turn-on’ VR outside of the MSFS2020 main screen (where the World is in the upper left) I would suffer some negative consequence. I now follow a particular startup process: I start Steam, start MSFS2020, wait for it to completely load to that main screen, then plug the G2 headset cable plug into the switch box, put on the headset to trigger the Mixed Reality Portal (MRP) to load, ensure I can peek under the headset to see my monitor and patiently wait for the Ctrl-Tab option to initiate VR to show up, then, click Ctrl-Tab and watch as the headset screen transitions from MRP to the MSFS2020 main screen in VR, I then proceed to interact with the program as I would in 2d and go fly.
This procedure has eliminated the issues I experienced before and has been very repeatable. I hope this helps.