If statement is true and console.log messaging works but won't return

Question

Hello in my code I am trying to check if a username is taken. The code goes into the if statement and prints the console.log "username exists" but it won't return true and always returns false.

  get(child(ref(db), "users/")).then((snapshot) => {
    if (snapshot.exists()) {
      const users = snapshot.val();
      for (const user in users) {
        if (users[user].username == username) {
          console.warn("username exists");
          return true;
        }
      }
    }
  });
  return false;
};