Keychain stored information are missing randomly when app goes in background for some time

Hello, some of our users are facing a problem after the update on iOS 15.

The app stores some sensitive information in keychain. Everything works properly when app is in foreground and moreover when the user is active with this across a short time frame.

However they complain that after some time (random time) that app is in background and they return to it, it has lost the keychain items and the app asks for a new registration.

Moreover we don’t do anything before didFinishLaunching. We also tried some other approaches that are proposed to some other threads in order to move some code that is related with user defaults or keychain in applicationProtectedDataDidBecomeAvailable but the issue wasn’t fixed.

The app in prior to iOS 15 versions works as expected without any problems.

Is there anything else that we can do?

Thank you in advance.