When using a trackpad connected to Apple Vision Pro on a mirrored Mac the trackpad stops working on the mirrored Mac when VPN is enabled on the mirrored Mac.
Also the keyboard connected to the Apple Vision Pro stops working on the Mirrored Mac. On the mirrored Mac I can see the iPad like cursor (round circle) and move it around but it does nothing. When I disconnect from VPN, control comes back and keyboard connect to AVP works again on the Mac
What kind of VPN are you using? If not using Network Extensions, probably going to have a bad time.
FWIW, the VPN I am using does not have this problem, so likely a configuration or implementation detail specific to your VPN software.
