This is not so common in modern houses these days, but it sometimes happened in old Japanese houses. When I examined the situation in detail, I found that it was caused by light entering through a small hole in a storm door and reflecting on a shoji (paper sliding door).
This may not seem to have anything to do with a camera, but in fact, this is the simplest way for a camera to work.
In other words, the dark room is the boxy part of the camera body, and the small gap in the shutter is the lens of the camera.
In this way, if there is a box with a dark interior and a small opening through which light can enter, the outside scenery that enters through the opening will appear on the inside wall of the box. This is a pinhole camera. Cameras use this mechanism.
A camera can take pictures without a lens, but it can only take very blurry pictures. Therefore, a lens is attached to the camera to make it possible to take beautiful pictures. By the way, a photograph cannot be taken without a film as well as a camera. Film is used to record the light that comes through the camera lens. When the film is taken out of the camera and placed in a developing solution, a picture emerges. This is then burned onto photographic paper to produce a photograph.