In just about any face texture image, the highest (sharpest) specular bits appear to be on the lips, followed by the nose and then forehead. In messing with this a bit on the non-dark-skinned texture images, I find that if I drop the blue multiple to 2 (from 4) then even without changing anything else the end-product image appears to have roughly the same overall tone as the original.

This is all eye-balling.

The contrast appears to be softened (less), dark colours a bit lighter, bright colours slightly less. The specular on the lower lip is still visible - however, less so.

I still don't know if I'm meant to change that blue multiple or not.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks