I've been watching this video again:
犹大模玩 第三季 第8期 prime1studio 《Suicide Squad》 Harley Quinn out of the box
https://youtu.be/cqUEnvvQhwA
As the statue rotates, i couldn't help but notice, the tattoo's on Harley's legs catch the light, thus are reflective to some degree. I have to assume they are some form of decal possibly covered in lacquer. I guess Prime 1 could not find a way to match the skin surface. For the moment, must guessing and assuming on my part.