Based on my observation, it’s not a fetish but more like they want to make the characters different from each other because the artist is suffering from same-face syndrome. If the skin tone is the same, the main characters will look like relatives or be hard to differentiate, which makes it less enjoyable to read.
Not a fetish, just creative choice. Also the skin color is intentional anyways cos the background of the characters, culture, history etc reflects to that skin color. Like theyre sporty and under the sun, lives by the beach, lives in the south, ancestors are from the south, or lifestyle/ work where u have to be under the sun more. Which shows the detail they pour into their works and craft. So no its not a fetish. What their fetish is they really like buff bottoms, so most of their works (especially after finding their signature) shows buff or normal bottoms (no twinks)

So, i noticed it few weeks ago that most of bwat manhwas have one common thing… one of main characters is brown skinned and the other is pale…
Is it like a signature for her or a fetish or idk what but for me its kinda offputting tbh, not that im racist or shit but… it just doesnt sit w me right ig…
dont get me wrong tho, i love her manhwas but when u think of it this is kinda weird