Why does the monitor switch to black-and-white video when it enters night vision mode instead of staying in color?

This is normal. In the dark, the camera uses night vision to help you see your baby more clearly, and night vision appears in black and white.

Full Answer:
When the inside of your car gets dark, the camera automatically switches to night vision mode.
Night vision uses special infrared light to help the camera see in the dark. Since this type of light does not show normal colors, the video changes to black and white.
This helps give you a clearer view of your baby’s face and movements in a dark car without turning on bright interior lights.