How to deal with uneven spots on photos taken at night?

When shooting at night, the camera you are referring to cannot lower the shutter speed, so the camera will automatically choose a higher sensitivity (ISO) to shoot. So what you say is "uneven color points, sometimes color blocks, causing color distortion." -collectively referred to as noise.

Noise restoration is more difficult in post-production. A complete repair is almost impossible. You can try to use soft light effect, or make a different old style with your own noise.