Glycerin / Glycerol (E422)
A multipurpose humectant that can come from palm oil (halal) or pork fat (haram).
Why this is a critical point
Glycerin is used as a humectant and sweetener in food, medicine, cosmetics, and even toothpaste. It can be made from vegetable oil (palm, coconut), which is halal, or as a byproduct of processing pork fat, which is haram. Without a stated source, its status is uncertain.
Halal alternative
Halal-certified vegetable glycerin, usually derived from palm or coconut oil.