Hmm, is this an 'appropriated' piece perhaps ? Using an artists work as influence and mildly changing it to a different style. So 'borrowing' elements of an artwork, to make a new artwork.
I think it is legal to appropriate art, but I could be wrong.
It's what Andy Warhol did with that pop art stuff.
I.E Campbells soup can, and appropriated the colours differently ? I think he got away with it.
What the other artists has done (aside from adding color) is slanted Han's head ever so slightly. At first I thought they'd done the mouth differently but upon further looks it is the angle of the head. It's slight, but if you keep on looking you can see it.