mode 7 background

While spending 5 minutes to look for your stuff ON THE JOB, I found this:

Code:

EE/8781:    BF00ECD2    LDA $D2EC00,X  (Overworld map and sky palettes)

I don't have time to look further but with what I saw in bank EE the sky color is also a question of gradients applied to the color, which make some portions of the sky darker. You might have to disable them.