Why is shaders 3D model too shiny when paint?

Your 3D model’s shader is too shiny when painting usually because the shader’s specular or metallic properties are set too high, or the roughness/gloss map isn’t balanced to reduce reflectivity. Specular controls light reflection (the "shine"), while metallic mimics metal’s natural gloss—too high values make the model overly glossy. A roughness map adds "mattness"; if it’s too smooth (low value), the surface stays shiny even with paint. To fix this, lower specular/metallic values slightly or adjust the roughness map to be more "rough" (higher value) in less shiny areas. You can also check if the paint texture’s gloss channel is accidentally boosting reflectivity.