I have a question on whether consumption of the "velvet" that naturally falls off the antlers of a deer is permissible to consume if put into a protein powder. There is a product I’m interested in that has this as an ingredient.

If it is used as medicine and it’s a medical necessity to use it (due to one’s health). Otherwise it’s not permissible because it is taken from a living animal. Now if the deer is slaughtered halal then it would be permissible to consume it’s antler velvet