If an error occurs when a user uses your deployed app, logs are left.
Looking at the log contents.

[cloud_firestore/permission-denied] The caller does not have permission to perform the specified operation. An error occurs. What’s strange is that all of the users experiencing this error are iOS devices (Android doesn’t experience it).
Looking at the Firestore DB, there is a rule that says request.auth != null, but it seems to throw an error when auth is turned off.
I’m curious why request.auth is turned off and why it only appears on iOS devices.

this is rule in Firestore

 match /collection/{document=**} {
        allow read: if true
      allow write: if request.auth != null
    }

   match /collection/{email}/subCollection/{document=**} {
        allow read: if request.auth != null && request.auth.token.email == email
    }

And!! iOS users often have their auth turned off even where rules aren’t needed. So is this ultimately a token issue?

I have tried to find the cause of the error and hope it is resolved.