Include of non-modular header inside framework module

[e-shawakri]

I always get this issue when I run an iOS project after adding flutter_appauth dependency:

Lexical or Preprocessor Issue (Xcode): Include of non-modular header inside framework module 'flutter_appauth.AppAuthIOSAuthorization': '/Users/emad/StudioProjects/d-ticket/ios/Pods/Headers/Public/AppAuth/AppAuth.h'
/Users/emad/.pub-cache/hosted/pub.dev/flutter_appauth-6.0.4/ios/Classes/AppAuthIOSAuthorization.h:0:8

Lexical or Preprocessor Issue (Xcode): Include of non-modular header inside framework module 'flutter_appauth.OIDExternalUserAgentIOSNoSSO': '/Users/emad/StudioProjects/d-ticket/ios/Pods/Headers/Public/AppAuth/AppAuth.h'
/Users/emad/.pub-cache/hosted/pub.dev/flutter_appauth-6.0.4/ios/Classes/OIDExternalUserAgentIOSNoSSO.h:19:8

Lexical or Preprocessor Issue (Xcode): Include of non-modular header inside framework module 'flutter_appauth.FlutterAppAuth': '/Users/emad/StudioProjects/d-ticket/ios/Pods/Headers/Public/AppAuth/AppAuth.h'
/Users/emad/.pub-cache/hosted/pub.dev/flutter_appauth-6.0.4/ios/Classes/FlutterAppAuth.h:6:8

Lexical or Preprocessor Issue (Xcode): Include of non-modular header inside framework module 'flutter_appauth.FlutterAppauthPlugin': '/Users/emad/StudioProjects/d-ticket/ios/Pods/Headers/Public/AppAuth/AppAuth.h'
/Users/emad/.pub-cache/hosted/pub.dev/flutter_appauth-6.0.4/ios/Classes/FlutterAppauthPlugin.h:10:8

Parse Issue (Xcode): Could not build module 'flutter_appauth'
/Users/emad/StudioProjects/d-ticket/ios/Runner/GeneratedPluginRegistrant.m:33:8

flutter_appauth version ==> 6.0.4, also with previous versions I got this issue.
I've tried to upgrade Flutter to the latest version but with no success.
I've tried cleaning the project and building it again but with no success.