DIAGNOSIS The infrared LEDs for night vision are either being blocked or the lens is dirty. The camera relies on these invisible LEDs to light up the dark, and if the lens is smudged or something is in front of the sensor, it scatters the light, causing a hazy, bright blob.
FIX First, clean the lens gently. 1) Unplug the camera. 2) Use a soft, dry microfiber cloth (like you'd use for glasses) and gently wipe the circular glass lens in the center. Don't use liquids or cleaners. 3) Also check that there's no spider web, dust, or object right in front of the camera. Plug it back in and check the feed after dark.
IF THAT DIDN'T WORK The issue might be a reflective surface in the camera's view. The IR light can bounce off a window, glossy picture frame, or mirror back into the lens, washing out the image. Try angling the camera slightly away from any shiny surfaces.
HEADS UP Don't put stickers or tape over the lens or the ring around it—that ring is where the infrared LEDs are. Covering them will completely ruin night vision.