Nope, definitely not light or any other type of interference. The actual device is making the noise when it kicks into night mode so that’s what sound the mic is picking up.
If you have the unit in your hand inside the house and its dark enough to go into night mode you can hear the noise when you put it up to your ear.
Very weird, I thought it was software based at first. Maybe wifi issues or something else interfering with my signal until I found this thread. All of us who posted a sample of the issues have the same exact noise and only happens when in night mode. It kind of ruled out many other possibilities.