There is a lot of fraud with UPI, specifically social engineering to obtain UPI OTP codes.

Since the card and the account haven't been previously associated, that's probably a risk model saying a human needs to verify the account before activation.

Indian cards also (I believe) have a mandatory 24 notice period prior to money being pulled - giving fraudsters a 24 hour starting gun to spend like crazy. That makes merchants that provide variable cost service on credit products twitchy.

https://support.stripe.com/questions/background-on-indian-go...