8bitdo Ultimate: turning controller off launches Big Picture Mode

[hjpaul7]

Your system information

• Steam client version (build number or date): 9/13
• Distribution (e.g. Ubuntu): Arch
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes
• Steam Logs: steam-logs.tar.gz
• GPU: Nvidia

Please describe your issue in as much detail as possible:

Turning the 8bitdo Ultimate controller off (press and hold guide button) launches Big Picture Mode as controller turns off. This doesn't happen with other controllers, such as the PS5 controller when pressing and holding the PS button to turn the controller off. Also happens on Stable.

Steps for reproducing this issue:

1. Turn controller off