The emissive is much more vibrant like it is supposed to be.
I tried playing around with the post processing settings but the only thing that helps is setting crush highlights to 1 but the problem with that is that it also changes the non emissive parts and just makes everything more vibrant. Setting the emissive amount higher just makes it more white, not more saturated.
Could you provide screenshots of the material editor graph for the materials in question.
If it looks fine in unlit mode I would consider the possibility of the specular highlights washing out the emissive areas. To help this mask out your emissive areas from the specular output in your material by having the emissive section black. This will prevent any light from washing it out.
I set roughness to 1, specular to 0 and metallic to 0 and it looks still washed out. The normal is just flat. So I assume it has nothing to do with the material. But the lighting affects how much it looks washed out, the brighter the surface is lit the more the emissive looks washed out.
I know it may not seem like a material issue however, I would still like that information provided (material graph) in order to help with this investigation. Could you also provide this information as well:
What kind of light are you using? Also could you provide light settings.
Is the lighting static, stationary, or Moveable?
Also try considering this workflow. Separate the emissive from the basecolor by making the area black on basecolor where the emissive is applied. That will give you more control over the color of your emissive since it blends with your base color additively.
