I think it's more of a standard to have red indicate a disconnected state. My Thinkpad T14s has a red dot on the webcam cover, wireless peripherals like mice have a red indicator when they're off, etc.
Edit: I also don't think it should be confused for the "activity being used" LED indicator. The disconnected indicator is just paint, not a light.
I was just thinking about how my dog kinda smells like Frito's a while back. I guess it's not just me. ๐