How did the light in the photo become a heart?

Well, you use a piece of paper (the same size as the aperture in front of the lens), cut a heart-shaped hole in it (preferably smaller than the aperture hole), and then cover it in front of the lens, and then the spots will all be heart-shaped.

Small DC is not easy to handle, because the diameter of the aperture hole is mostly less than 5 mm. It's better to use Nikon or Canon SLR, and buy 1.8/50mm lens from 600 to 700 yuan.