Ah, if you will see here,

You'll notice your blotchy patches are on your art but not as noticeable.
In your post-Bright, you can see it has some compression artifacts on the skin but the blotches are noticeable in the pre-Bright version just as much.
After seeing your flat art and in game screens, I'm reasonably sure what is more noticeable in your screens is caused by video setting and/or game rendering, different gamma etc. Do you have any other way to view it? What I think we are seeing is a more contrasty version of your art.
Still, your original is blotchy, not bad looking in flat format, but blotchy. Those blotches are almost certainly a product over-saturation or "visual" distortion, the colors have been changed, modified, messed with too much. Was this by any chance a blue Corsair that you've changed to OD? This kind of thing is easy to get when changing one color to another.
How is your file set up? If in layers, selectively turn the layers off until you don't see any sign of blotchies or until you get to your base layer. Chances are, you'll be able to smooth it out but either way, you can see where the blotchies are coming from.