Cannot access Firebase Storage with or without authentication (web)

I want to use Firebase Storage (web version 9.6.0) but the access to Firebase Storage is being denied with the following error:

unhandledRejection: FirebaseError: Firebase Storage: User is not authenticated, please authenticate using Firebase Authentication and try again. (storage/unauthenticated)

You would want to say to me that I just need the user to be authenticated, but two problems:

• the user is already authenticated (getAuth().currentUser returns something)

• the rules in Firebase Storage don't say that a user needs to be authenticated:

rules_version = '2';
service firebase.storage {
  match /b/{bucket}/o {
    match /{allPaths=**} {
      allow read: if true;
      allow write: if request.auth != null;
    }
  }
}

The problem is caused when I try this:

// initializeApp(config) etc.

const storage = getStorage() // enabled in Firebase console
const a_correct_path = ""
const reference = ref(storage, a_correct_path) // this is working (I get the right reference)
const url = getDownloadURL(reference) // this throws the error

NOTE: Because I have already had problems with it, please not that I'm using App Check which I have enforced for the Storage feature.

Why did I do wrong?

from Cannot access Firebase Storage with or without authentication (web)