Glow Item Frames have different lighting textures

When I place the new Glow Item Frames in the day time they look normal. When it becomes night time the Glow Item Frames become darker in texture, this would seem normal however it still happens when you have the frame lit to level 15 as I showed below. One picture was taken at day time and one at night. the light level in the room never changed however the item frame becomes dark at night time.