3 days after a Cosmelan 1 Peel on my knee caps, they have become very dark and are not peeling. Is this normal?

I've never heard of apply Cosmelan to the kneecaps. It's is designed for the face. You don't have to peel from the Cosmelan to have a good result, but you need to make sure you are using the Cosmelan 2 and Vitamin K product. And using sunscreen. "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."