In-app purchase asks every time to sign-in Apple ID and password on IPAD specifically when installed from test flight

Question

My app's IAP works fine on local build for iPhones and IPAD for iOS 15.1 but when I upload it on a test flight, it keeps on displaying enter apple id and password even I have signed into it on the app store using a sandbox account. This problem occurs only on iPad iOS 15.1 and works fine for every other device that too when I install the app from a test flight. When I take a local build from Xcode, the issue does not happen.

Answer 1

Use your real account not the sandbox for TestFlight