So, I was playing around with the principaled shader and I noticed that when I included a shadow catcher to my scene, it changed the color/texture of my object. How do I fix it or is it a bug?
So, I figure the answer. It's because the first picture there is no plane under the head but the one with the shadow catcher has a plane which I guess reflects the light which brighten the head. My nodes setup is simple, it's principled shader to the material output.