But Apple also announced a new longer 2.5x telephoto camera on the iPhone 12 Pro Max, which many expected would be able to shoot Night Mode shots, despite Apple's deliberate silence on the matter. Well, it doesn't.
camera sometimes works at night and that depends on the available light. If the luminance goes below some fixed point, the phone uses its primary camera and digitally zooms instead."
And that stems from the difference between the main camera and the zoom camera – in all cases the main sensor is larger than the sensor behind the zoom lens, so many phones use the larger sensor in lower light. The first dual-camera iPhone 7 Plus would similarly use digital zoom from its main camera, instead of using its zoom camera at night.