So I have this weird problem with the light reflection. On bright texture the reflection is too much, but on the darker texture, the reflection is too little. I am using the same light intensity, but the reflection increment looks like it is spiking.
Is this raw white texture screenshot above your base texture? The point is the reflection (and refraction) intensity considers both the base/diffuse and the normal map? You can lower this difference by making your white texture less white and also by lowering your normal map level on the white material (compared to the dark one).
Or you can adjust your reflection/refraction level on this material. Note that the intensity of reflection can also be affected by post-processing, i.e. when pushing the exposure level.
Something like that, yes. Point is the more difference you have between the white and black, the more sensitive will be your input for reflection under light. You also need to keep some ‘material’ in your texture. If the pixel is just plain white, than the light can only add to the white (and ‘explode’ the texture). So, the white material needs to be light gray (because white with no light or under shadow, is actually gray (unless it has an emissive). BTW, you can further enhance the whitish aspect by using your (light gray or medium gray) texture also as an emissive texture with just a very low level (~0.003) for a ‘simili-leather’ type of material (like yours may be? looks to me like a technical wear that should have a bit of a ‘plastic’ effect under light, correct?
Edit: Forgot to mention that there are at least 2 other parameters you can set/tweak. You can lower the level of your base/diffuse on the white material and push it a little above 1 (~1.3-1.4) for the colored/darker material. You might also want to adjust the specular (level and color).