I’ve a Outdoor Cam Pro (firmware version 18.104.22.168, latest at the moment) that during complete darkness switches night vision off and back on roughly every 30 minutes. You can hear the clicking sound when the camera switches night vision on and off.
Here is how it looks like in my Synology NAS in a room that is completely dark (no changes in light or movement). The camera has a completely free view (eg nothing is reflecting the night vision lights):
Not sure if this is related to a faulty product hence any guidance is appreciated!