API Calls not working in Mobile App

I made a customer GPT with a simple API call to fetch a JSON file from my S3 bucket. This works fine when I do it in my browser. Up till last week it also worked very good in the mobile chatGPT app (on Android). Now when I try to call the API on my phone it is not retrieving the JSON file. When I do exactly the same in my browser (on my laptop) it works flawless.

Is there a different way that the mobile app is calling APIs compared to chatGPT in the browser?