The best case would be Alipay 0% which would transfer CNY into PB so no exchange fee. But this option isn't available to most of you. Source: about 1 year ago

Alipay is a super app designed to offer a bouquet of services to bring convenience into your everyday life. Trusted by 450 million users, Alipay’s offerings span from allowing its users to make payments (send, receive, and spend money with ease), manage finances, choose a suitable insurance scheme, hail a cab or even order in from a favourite restaurant. Source: over 2 years ago

They may be using something like Sift for security checking and something of yours was flagged. Source: over 1 year ago

But sorry to break it to you, this has been done at a really large scale already although most consumers are not aware. One big player here is https://sift.com/ Almost every major retailer uses their service exactly for the reasons you mention. Source: almost 3 years ago

Reddit, for one. A pretty big list on their homepage. Source: almost 3 years ago