Adding images with FF Data Manager

Hi everyone. I've encountered a strange issue that I'm trying to resolve. When I attempt to save an image on FF Data Manager, it fails to save the document (it just loads for 1 second and then nothing happens).

I've discovered a solution - it's related to Firestore storage rules. By default, they look like this:

service firebase.storage {
  match /b/{bucket}/o {
    match /{allPaths=**} {
      allow read, write: if false;
    }

Changing them to the following seems to help:

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

However, I'm not sure if it's wise to grant all authenticated users permission to write.

My question is: Is there a solution to grant this permission exclusively to FF admins?