Missing or insufficient permissions errors after logout

Since the error message mentions onSnapshot I assume you're accessing the Firebase Database or Cloud Firestore somewhere in your code.

The data that you're reading from the database has security rules configured that require that the user is authenticated. So when you log the user out, that requirement is no longer met, the app loses access to that data, and the observer is canceled.

To prevent this error from appearing, remove the observer before logging the user out.

Update

To remove the observer/listener follow the patterns shown in the Firestore documentation on detaching a listener. First keep a reference to the return value you get from onSnapshot.

var unsubscribe = this.fbDataServ.getPlacesByUserAllowed().onSnapshot(placeReceived=> {

Then call that unsubscribe() just before signing the user out like this:

unsubscribe();