How does Apple's 7-night shooting make the photos clearer?

Photography lights and flashlights must be added to make them bright and clear.

When it is possible to take clear photos with iPhone at night, generally speaking, the effect will be better when there is more light in the photos.

In the case of insufficient light (such as indoor shooting), less light reaches the camera sensor. In order to let enough light reach the sensor to produce an appropriately exposed image, the shutter must remain open for a longer time. Any action when the shutter is open (including the action of the iPhone itself and the movement of the subject) will lead to blurred photos. The longer the shutter is open, the more actions may be taken (leading to more blurring).

When the iPhone doesn't start to manually adjust the shutter speed, the shutter will stay open for a shorter time when there is enough light.

So if you can take measures to increase the amount of light entering the photos (such as shooting outdoors or turning on the lights), you will get clearer photos.