The only thing I see different is located between the AC unit in the middle and the rear vent. Shadows are what people are seeing as addressed below. The bottom of the vent is above / right at the level of the window. As such its shadow would be under it in the window area in daylight photo while the vent's position is clearly visible in the night photo. Look between the AC unit and the rear vent in the night photo, something is present there.