I just want to post again, just to say that the most recent Chinese translation of the new story has a very specific paragraph on hair of vampires.

So read that to know what is canon to Overlord.

<!Hair is fixed in length at the point of undeath conversion. When you cut the hair, it is treated as a type of damage and the hair that is cut off turns to dust. The hair on the head stays cut and unchanged, it does not grow back, but any kind of (undead) healing would instantly "regenerate" the hair back to the default length. Ainz wondered what happens if someone with missing limbs get converted to a vampire, but he doesn't know the answer.!>