Apps offering Apple Pay as a checkout option need a working, tested implementation and have to display the official Apple Pay mark and button per Apple's design requirements, not a custom-styled substitute.
Usually a minor but real trigger when a custom-styled "Pay with Apple Pay" button doesn't match Apple's required button treatment.
"Your app's Apple Pay button does not comply with the required visual design guidelines, per guideline 4.9."
Guideline 4.9 applies to apps that offer Apple Pay. The integration has to work properly and use the official Apple Pay mark and button as set out in Apple's design requirements. A custom-styled substitute for the button, or a payment flow that is incomplete, is a small but real reason for rejection that reviewers notice quickly.
Apple Pay is a trusted payment method, and its appearance signals that to customers. If every app styled its own version, people could be fooled by imitations, and the brand would lose its value as a sign of security. Requiring the official button and a functioning implementation helps users recognise the real thing and ensures the payment flow behaves as people expect from the service.
Digital goods generally use In-App Purchase instead.
Apple publishes design requirements for the button and mark.
Apple Pay requires a payment processing arrangement, separate from App Review.
Platform rules change often. This page is a plain-language explanation written by AppReviewFix, not official guidance. Check the current App Store Review Guidelines for the exact wording.