I feel like it’s just the lighting
I don’t think taekjoo was THAT dark in the first season so I don’t see much difference, but could possibly be cause of lighting or the locations
In colder climates/weather where you're not as exposed to the sun, no matter how dark you are you slowly get lighter! Hence why in the colder climates they're so pale and in the more sun heavy climates they're darker
And in mixed weather climates you get darker in the summer/spring and lighter in the winter/fall
I don't give a fuck about how zhenya looks but did my taekjoo king's skin color really got lighter in new art style or am i seeing things ಠ_ಠ