Artist's Pages:
https://www.furaffinity.net/user/xanderdwulfe
https://www.deviantart.com/skeletalboydecoy
https://twitter.com/Skeletal_boy
https://inkbunny.net/XanderDWulfe
https://bsky.app/profile/skeletalboydecoy.bsky.social

For their webcomic High School Death Party:
https://inkbunny.net/highschooldeathparty
https://www.deviantart.com/highschooldeathparty
https://www.furaffinity.net/user/highschooldeathparty/
https://twitter.com/HSDeathParty

Commissioner's Page:
https://www.furaffinity.net/user/doctorviolet

I think he was using a reference for Niffty that didn't have neutral lighting because she canonically has about the same color skin as Charlie

Base +6

@Itachi-kun | Nope, actually! It's just using the pilot designs, where Niffty actually Did have yellow-ish skin!
(Pretty sure they specifically changed that because they thought that was a little bit racist, since Niffty's actually Japanese)

Base +6