degisken ata
private EventHandler<ValueChangedEventArgs> roomValueChangedHandler;

private void StartRoomListener(string oda)
    {
        if (!isRoomListenerActive)
        {
            isRoomListenerActive = true;
 
            databaseReference.Child("odalar2").Child(oda).Child("durum").ValueChanged += HandleRoomValueChanged;
        }
    }

satırını böyle degiştir

    private void StartRoomListener(string oda)
    {
        if (!isRoomListenerActive)
        {
            isRoomListenerActive = true;
            roomValueChangedHandler = HandleRoomValueChanged;
            databaseReference.Child("odalar2").Child(oda).Child("durum").ValueChanged += roomValueChangedHandler;
        }
    }

satirini

    private void StopRoomListener(string oda)
    {
        if (isRoomListenerActive)
        {
            isRoomListenerActive = false;
            databaseReference.Child("odalar2").Child(oda).Child("durum").ValueChanged -= HandleRoomValueChanged;
        }
    }

böyle degiştir

   private void StopRoomListener(string oda)
    {
        if (isRoomListenerActive)
        {
            isRoomListenerActive = false;
            if (roomValueChangedHandler != null)
            {
                databaseReference.Child("odalar2").Child(oda).Child("durum").ValueChanged -= roomValueChangedHandler;
                roomValueChangedHandler = null;
            }
        }
    }