Diagnosis
That "foggy" look at night is usually caused by infrared light reflecting back into the lens. It's most common when the camera is installed too close to a wall, eaves, or window, or if the lens is dirty.
How to Fix It
First, give the camera lens and the clear dome around the IR LEDs a good cleaning with a soft, microfiber cloth. Fingerprints or spider webs cause major glare. Next, check the camera's physical position. The IR LEDs fire out in a pattern. Make sure there's at least a foot of clear space in front of and to the sides of the camera. If it's tucked right under a soffit, the light bounces off that surface and back into the lens, creating a white haze.
If That Didn't Work
Log into the camera's settings via the app. Look for the Night Vision or IR settings. Try switching the mode from "Auto" to "Manual" and adjust the IR intensity slider down. Sometimes on Auto, it maxes out the IR brightness unnecessarily, worsening the glare.
Heads Up
Heavy rain, snow, or dust in the air will also scatter the IR light and cause temporary foggy video. That's just a physics limitation of infrared.