I am trying to use security rules in order to limit what information about other users is able to see one authenticated user, depending on if these users are in the same department or not. I have about 50 users in Firebase Auth whose ids are correlated with the document id in the users collection (usuarios) in firestore. IN the collection, each document have a parameter called departments which is an array of strings, and it represents the departments the user belongs to. Then my goal is to limit the read access into the users which have any department in common. For this I created that security rule: