Small dark pattern, or just bad timing?
I paid for a year of Google AI Pro. Only then did a pop-up suggest I join Google Play Points to earn points on every purchase. Not the purchase I'd just made, though, and Google Support says it can't be added retroactively.
I don't think anyone designed it to sting. But a rewards offer that appears one screen after the biggest spend chips away at trust.
Offer it before checkout.