Question:

Why are there stains and uneven colors visible when checking the images I took?

Answer:

The issue you're experiencing is known as the Moire phenomenon. It occurs due to interference between the image sensor's pixels and either the display pixels or objects with periodic patterns, like mosquito nets. Additionally, it can happen when photographing subjects with slopes perpendicular or parallel to the image sensor.

To avoid this problem, try adjusting the distance between the device and objects, or changing the shooting angle. Alternatively, if you change the screen resolution while viewing the images, the Moire phenomenon may disappear.