This game allows the use of various non-conventional controllers. Mics, VR headgear, stuff that face tracks to control your FoV ingame.
My guess is that the mic (or more) is enabled for that reason. This makes your webcam driver turn on the entire cam I guess... (or the LED in it?)
Not sure how to disable it. I'm not keen on the mic listening in on me, when I'm not even trying to use it. Thinking about it; comms menu (shift + up) does list audio message, so I guess I could just go and call in with other CMDRs.