I’m using the Standard (Specular setup) shader in 2019.3.0f6 and for reasons I can’t understand all the textures applied to this material look dark and desaturated. The most notable problem is that large areas that are pure white in the source issue appear grey (close to 128,128,128) both in the material preview window and in-scene lit by a white directional light. I feel like I must have some fundamental misunderstanding of the shader or of the project’s render settings, but I can’t figure out what it is.
Do your textures have an alpha channel?
Does it persist if you remove the specular map and/or reduce the smoothness a bit?
A very high specular (as you seem to have on the poles) can result in dimming of highlights or desaturation of colours.
Low Specular, Low Smoothness Example:
High Specular, High Smoothness Example:
You might also want to check if the Texture has sRGB checked or not, as this affects the colours when in the default color space.