Magento/Stripe payments issue

Platform: Magento 2.4.3-p3 backend with Stripe Payments module

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Objective:
We are experiencing payment flow errors on iOS devices using Stripe and Apple Pay through a Flutter app connected to a Magento 2.4.3-p3 backend. The goal is to identify, diagnose, and resolve these issues for a stable, production-ready checkout experience.

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Key Responsibilities:
- Inspect and align Magento 2 REST API responses with Flutter app expectations.
- Correct JSON vs. HTML response handling between Magento and Flutter (ensure consistent JSON responses).
- Validate Stripe Apple Pay merchant IDs and configuration.
- Test and verify complete checkout flow using Stripe test keys.
- Ensure compatibility between iOS payment logic and Magento Stripe module.

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Required Skills:
- Strong understanding of Magento 2 API architecture and Stripe module internals.
- Experience with Stripe and Apple Pay integration on iOS.
- Proficiency in debugging tools: Postman, cURL, Stripe dashboard logs.
- Familiarity with Flutter (Dart) and API communication handling is a plus.
- Ability to coordinate fixes across backend (Magento) and frontend (iOS/Flutter).

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Typical Magento Error Cases (to be resolved):
- FormatException: Unexpected character
- No such entity with %fieldName = %fieldValue
- The requested Payment Method is not available.

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Access & Environment:
- Magento 2.4.3-p3 running on Ubuntu with Stripe Payments module
- Access to Stripe Dashboard (test & live keys)
- Magento Admin credentials (sandbox)
- API endpoint access for manual testing

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To Apply:
Include examples of previous Stripe + Apple Pay iOS integrations you’ve completed.
Describe the debugging tools or frameworks you use for REST / payment API tracing.