It was discussed in social media when he appeared in KMIYC and some where attacking the artist for whitewashing Dane. Considereing his discription in KLM novel and later he seemed to be white. It was the KML art that made people think otherwise. So some people searched and one found where the author gave a discripton of Grayson and Dane for an event on Ridibooks ( https://ridibooks.com/event/82669 ). And that person said what the author used the korean wording for being tanned/roasted by the sun, and if Dane really had natural dark skin it would have been written differently.
And Spoiler considering the background
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Dane's mom has the same hair and eye color as Dane, and she was raped by three alphas.
And Dane was the result of that rape. And they got way with it.
As you said it's a Korean author, so better not get into problematic stuff in that way.

Am I the only one who thinks Dane is African American or biracial?