Ionic 3 Firebase Google Auth redirects to localhost instead of app - firebase

Question

Im using AngularFire2 in my Ionic 3 Project. I have implemented Facebook and Google Login which worked before but somehow it stopped working (maybe because of changes in the Firebase SDK or Google?).
The problem Im facing now is that once a user logs in through google with redirect he logs in but doesnt get redirect back in my app. Instead google just displays this page on redirect:
Here is the Code im using for SignIn:
private oauthSignIn(provider: AuthProv) {
if (!(<any>window).cordova) {
return this.afAuth.auth.signInWithPopup(provider).then((user) => {
this.user = user.user;
});
} else {
return this.afAuth.auth.signInWithRedirect(provider)
.then(() => {
return this.afAuth.auth.getRedirectResult().then(result => {
this.user = result.user;
});
});
}
}
This code is from the AngularFire2 Documentation itself so I cant find any errors.
This is my package.json:
"dependencies": {
"#angular/animations": "5.2.11",
"#angular/common": "5.2.11",
"#angular/compiler": "5.2.11",
"#angular/compiler-cli": "5.2.11",
"#angular/core": "5.2.11",
"#angular/forms": "5.2.11",
"#angular/http": "5.2.11",
"#angular/platform-browser": "5.2.11",
"#angular/platform-browser-dynamic": "5.2.11",
"#ionic-native/admob-plus": "^5.8.0",
"#ionic-native/app-version": "^4.20.0",
"#ionic-native/core": "~4.20.0",
"#ionic-native/keyboard": "^5.8.0",
"#ionic-native/navigation-bar": "^5.8.0",
"#ionic-native/splash-screen": "~4.20.0",
"#ionic-native/status-bar": "~4.20.0",
"#ionic/storage": "2.2.0",
"#ultimate/ngxerrors": "^1.4.0",
"angularfire2": "^5.2.1",
"cordova-admob-plus": "0.30.0",
"cordova-android": "7.1.4",
"cordova-plugin-app-update": "2.0.2",
"cordova-plugin-app-version": "0.1.9",
"cordova-plugin-appversion": "1.0.0",
"cordova-plugin-device": "^2.0.2",
"cordova-plugin-ionic-keyboard": "^2.1.3",
"cordova-plugin-ionic-webview": "4.1.1",
"cordova-plugin-navigationbar": "1.0.31",
"cordova-plugin-network-information": "git+https://github.com/apache/cordova-plugin-network-information.git",
"cordova-plugin-splashscreen": "^5.0.2",
"cordova-plugin-startapp-ads": "git+https://github.com/lreiner/cordova-plugin-startapp-ads.git",
"cordova-plugin-statusbar": "^2.4.2",
"cordova-plugin-whitelist": "^1.3.3",
"firebase": "^6.1.1",
"ionic-admob": "^0.19.6",
"ionic-angular": "3.9.5",
"ionicons": "3.0.0",
"phonegap-plugin-mobile-accessibility": "git+https://github.com/phonegap/phonegap-mobile-accessibility.git",
"promise-polyfill": "^8.1.3",
"rxjs": "5.5.11",
"sw-toolbox": "3.6.0",
"zone.js": "0.8.29"
},
I have already tried this Solution and added:
<preference name="CordovaWebViewEngine" value="CDVUIWebViewEngine" />
<allow-navigation href="http://*" />
to my config.xml which also didnt change anything.
I also have tried to downgrade
"cordova-plugin-ionic-webview": "4.1.1",
which also didnt work.
My Google WebClient has the right ClientID, Secred and Redirect URL like in the Firebase Console.
So how can I solve this behavior?