> There is no other way to pay other than via the app.
Seems you and Apple have different definitions of that statement. Using Stripe is not 'via the app' the way they see it.
Apple's is that 'via the app' means iAP proper, and the user's iTunes account credit card. That's the definition that counts where "Our app offers in-app purchases <clip>". AP is a payment mechanism, not a billing scheme.
>Do we have to use Apple Pay now? Is it obligatory?
IAP vs. Apple Pay ...two different things, naturally
Apple Pay is just a payment scheme/mechanism that connects to a payment provider/processor, so Apple Pay doesn't handle the actual payment itself. IAP is a transaction process, which again, involves direct billing via iTunes, where Apple takes it’s usual 30%.
Apple has this to say about that:
Apple Pay APIs:
3.3.42 Your Application may use the Apple Pay APIs solely for the purpose of facilitating payment transactions that are made through Your Application, and only for the purchase of goods and services that are to be used outside of any iOS Product. For clarity, nothing in this Section 3.3.42 supplants any of the rules or requirements for the use of the In-App Purchase API, including but not limited to Section 3.3.3 and the guidelines.
In addition:
- You acknowledge and agree that Apple is not a party to any payment transactions facilitated through the use of the Apple Pay APIs and is not responsible for any such transactions, including but not limited to the unavailability of any end-user payment cards or payment fraud. Such payment transactions are between You and Your bank, acquirer, card networks, or other parties You utilize for transaction processing, and You are responsible for complying with any agreements You have with such third parties. In some cases, such agreements may contain terms specifying specific rights, obligations or limitations that You accept and assume in connection with Your decision to utilize the functionality of the Apple Pay APIs.
And remember, Apple doesn't get their Apple/dev 30% split off a transaction when you buy/sell anything w/Apple Pay. As an example, Apple Pay reportedly collects 0.15 percent of each purchase from banks in the United States.
You got away with it before...you're flagged now. Done, until you change your business model. One question may be how you feel about Apple taking 30% of what the user shells out.
Ref.: 3.1.2 Subscriptions