It’s unlikely the camera is faulty. The most likely cause is a small insect, such as a moth, flying very close to the camera and nearby light source at night. Because it is so close to the lens, it falls far out of focus and appears as a large bright white blob or "orb." The light near the camera makes this more obvious and can also trigger motion alerts. If it only happens at night and near a light source, that strongly points to insects rather than a sensor problem.