>>510269210they probably didn't even think about it or care, the point of the mosaic was to celebrate his major deed, not on making a photorealistic portrait
but the fact that Plutarch, who is writing a biography unlike them, feels compelled to say "hey, by the way, regarding his looks, the depiction from Apelles makes him darker than he was, for he was white(leukos)", is also significative, why would Plutarch do it