It is a money grab from Amazon I'm sure. They want to make a deal with meta to get paid for access. Maybe also worried about liability I imagine on accidental unauthorized purchases?
The generally quoted return rate is 5% to 15% (and it varies by category). If Muse identified purchases are generating returns of 10% to 30%, then amazon is probably going to crack down on it. (Amazon Sellers pay from 30% to 50% for customer returns from their own pockets. https://medium.com/@myrealprofit/how-much-do-refunds-really-... )