Here - Amazon eligible for 5% Cashback via Millennia RuPay CC UPI (After complaint manually credited) -
HDFC Bank’s credit card software doesn’t yet have the full UPI data, that’s why they are crediting it manually. Hopefully after a few months it will start coming automatically. However, for some people, the 5% cashback via UPI has already been credited automatically (Maybe HDFC doesn’t yet have the data for all 5% cb merchant UPI IDs).