Repro steps:
Run mstsc from the client machine and connect to the WIN10 VM in full screen mode
Open an Edge window. Don't maximize. Leave it floating. Resize it so it covers about 1/4 of your screen.
Move the Edge window to the lower right corner of the screen.
Disconnect the remote session
Reconnect to the VM in full screen mode again
Notice the Edge window is now moved up and to the left.