That’s for sending and receiving local network traffic, eg. talking to devices on the same subnet, and discovery of Chromecast and similar targets.
Edit: AirPlay does not require this permission.
Edit: AirPlay does not require this permission.
I take this popup to mean that they want to fingerprint and locate my home network or backdoor it somehow. I ALWAYS deny this access unless the app specifically requires it, and that is rare.
WiFi based geolocationing should be a well known privacy threat by now. The popup should really communicate that better and provide tighter controls.
If anything, I usually see this for apps that want to do playback via Chromecast/Miracast. The well-behaved apps wait until the user interacts with Chromecast output, the iffier ones ask on first launch.
So far there doesn't seem to be any traction by Google to migrate to this.