Terrain Colors and Photoshop Color Switches Grayscale Colors

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So the problem I'm experiencing is that when I choose one darker colour the levels are different from one another I got a few screenshots to show what I mean I can't see what I'm during wrong. I might be dumb in the sense but I'm here asking for some help. Let me know what to provide to help you. Help me better.
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Note: I Tried to change the darker Colors one bit by one bit and that didn't work could someone explain the Terrain Level to me and how they work as a whole.
Note: Substance Map Provided were not provided not sure how important it was but wanted to leave that here aswell
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