FBX Export has some weird material shading
Okay, I have this model that I painted. I exported it a couple days ago as an FBX file and imported it into unity with no issues at all. But I had to go back and change the weight paint slightly. When I export it now, I have this weird issue with the material colors not blending together (I don't know how else to describe it). The intersection of the fur and the side of the face has a sharp line from where the two surfaces are being shaded differently (They are painted the exact same color, so I assume its shadows from somewhere).
The first Image is with the viewport shading set to solid, and is how it previously exported, and how I would like it to be exported.
The second image is with the viewport shading set to material preview, and is how it is now being exported which is not how it was previously, and not what I want.
Please let me know if anyone might understand what is going on... Is it something in the FBX export settings that I'm not understanding? Or maybe a material setting I cant find? I am struggling...