Why does lighting leave stripes on textures?

Question

Unity

There are several models, including those assembled from unity primitives. I do a day / night cycle and in the evening such a striped effect appears on the textures (on the screen below). How to fix it?

I turn the sun like this:

void Update() {
  if (isEnabled) {
    timer += Time.deltaTime;
    if (timer >= 1) {
      timer = 0;
      Tick();
      sun.transform.Rotate(0.25f, 0f, 0f);
    }
  }
}

Answer 1

It looks like the texture is tiled in Y, and the texture itself is gradient, hence the effect