After creating a half-ghoul character, I noticed the character's hands were pink.

I have no other mods that edit how characters look.

I feel it may be because of the pip-boy 2500 mod. But when I uninstalled it, the hands were still pink and the pip-boy was invisible!

I've tried uninstalling / reinstalling and reactivating archive invalidation every time.

Anyone know whats going on here?

try a fresh install well in your case install completely from scratch delete your saves for him and re install the mod making a new character and save. Note you can move your saves out of the save folder in doc and paste them later, and they work, careful not to mess up your mod list though.

Seems to be a common problem with ghoul race mods. Suss out "pink hands fix" or "no pink hands" and see what's out there.