Deserialization of JSON from Firebase to load data

i was wondering if you could help me with an issue i have with firebase and databases! I have a class that saves variables into an array. i have managed to send that json file to firebase and i can debug it to see its correct when i load the games database but i cannot set those variables to the game. the class is like this :

   [System.Serializable]
   public class LevelItem
   {
       public bool unlocked;
       public int starAchieved;
   }
   [System.Serializable]
   public class LevelData
   {
       [Header("Primary Set")]
       public int lastUnlockedLevel = 0;
       public LevelItem[] levelItemArray;
   }

to save it to firebase i do this

string levels = JsonUtility.ToJson(LevelSystemManager.Instance.LevelData);
reference.Child(data).Child("Sets").Child("Art").SetValueAsync(levels);

and i am trying to retrieve it and set those values (lastUnlocked , star achieved , unlocked and the levelItemArray) back to the game. my other variables like difficulty work fine with this :

LevelSystemManager.Instance.Bundles.difficulty = int.Parse(snapshot.Child("Settings").Child("Difficulty").GetRawJsonValue());

but i cannot load the whole levelData class back to the game! any tips or help? when i was saving the json localy i was doing it like this to load the values

string levelDataString = System.IO.File.ReadAllText(Application.persistentDataPath + "/LevelData.json");
LevelData levelData = JsonUtility.FromJson<LevelData>(levelDataString);
if (levelData != null)
     {
LevelSystemManager.Instance.LevelData.levelItemArray = levelData.levelItemArray;
LevelSystemManager.Instance.LevelData.lastUnlockedLevel = levelData.lastUnlockedLevel;
}

but this approach wont work with firebase

i did come close i think by doing this , in which the debug does show the json in the console.

var json = snapshot.Child("Sets").Child("Art").GetRawJsonValue();
LevelData levelData = JsonUtility.FromJson<LevelData>(json);
Debug.Log(json);
 
LevelSystemManager.Instance.LevelData.levelItemArray = levelData.levelItemArray;
LevelSystemManager.Instance.LevelData.lastUnlockedLevel = levelData.lastUnlockedLevel;

but this gives an error ArgumentException: JSON must represent an object type. but when i do save it localy everything works out

The JSON that gets saved localy is this one

{"lastUnlockedLevel":1,"levelItemArray":[{"unlocked":true,"starAchieved":1},{"unlocked":true,"starAchieved":0},{"unlocked":false,"starAchieved":0},{"unlocked":false,"starAchieved":0},{"unlocked":false,"starAchieved":0},{"unlocked":false,"starAchieved":0},{"unlocked":false,"starAchieved":0},{"unlocked":false,"starAchieved":0},{"unlocked":false,"starAchieved":0},{"unlocked":false,"starAchieved":0}]}

and this is the one that gets saved on firebase

{
  "Purchases" : {
    "allsets" : 0,
    "animalSet" : 0,
    "architecture" : 0,
    "nature" : 0,
    "noAds" : 0,
    "technology" : 0,
    "vehicles" : 0
  },
  "Sets" : {
    "Art" : "{\"lastUnlockedLevel\":1,\"levelItemArray\":[{\"unlocked\":true,\"starAchieved\":3},{\"unlocked\":true,\"starAchieved\":0}]}"
  },
  "Settings" : {
    "Difficulty" : 1
  }
}

As you can see i do have more classes saved there which like my difficulty example work just fine . my whole issue is that i cannot load back the entire LevelData Class and set it to the games variables.Thank you!

EDIT! so far i did manage to make it load by giving the raw json to the string but this is not good for actually loading things

string json = snapshot.Child("Sets").Child("Art").GetRawJsonValue(); // levelDataString
LevelData levelData = JsonUtility.FromJson<LevelData>("{\"lastUnlockedLevel\":1,\"levelItemArray\":[{\"unlocked\":true,\"starAchieved\":1},{\"unlocked\":false,\"starAchieved\":1}]}");
Debug.Log(json);

LevelSystemManager.Instance.LevelData.levelItemArray = levelData.levelItemArray;
LevelSystemManager.Instance.LevelData.lastUnlockedLevel = levelData.lastUnlockedLevel;

I still need to be able to parse that JSON as it is and i dont know why im still getting errors when i try it like this

string json = snapshot.Child("Sets").Child("Art").GetRawJsonValue();
LevelData levelData = JsonUtility.FromJson<LevelData>(json);