Fog in dimension changing colors

I have a problem in my custom dimension where the fog changes colors depending on where you look. It just goes from black to orange when turning to a different direction. I don't know what's causing this. It looks as if it's imitating the fog in the overworld when the time changes, but I have imitate overworld behavior, has sky light source, and disable ambient light source off. Any way to fix this so the fog stays as a dark purple?