Flutter App Mobile Data Issue

I'm experiencing an unknown error when starting a POST request on my Flutter app using mobile data. The app works fine with Wi-Fi, and I've confirmed that all mobile data permissions are granted. I am trying to use iyzico payment system on ios and works fine with wifi and even works fine when debugging with mobile data but production works only with wifi.

Requirements:
- Diagnose and fix the unknown error causing the POST request failure on mobile data.
- Ensure the app functions correctly with mobile data, similar to its performance on Wi-Fi.

Ideal Skills and Experience:
- Proficient in Flutter development.
- Strong understanding of network requests and mobile data handling in apps.
- Experience with debugging unknown errors in Flutter applications.