joined message delete time

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hi, I have a problem when a player joins I want that Photon sends a message as Player234 joined, but unity doesn't send me an error and nothing is on the screen.
I already had the problem solved and it worked perfectly for me but I changed it because with that code I did not know how to delete it when time passed and with this, I did know but still, nothing comes out, it helps.
[System.Serializable]
    public class JoinMessage
    {
        public string message;
        public float timer = 0;
    }

    List<JoinMessage> joinMessages = new List<JoinMessage>();
void Update()
    {
        //hide message
        for (int i = 0; i < joinMessages.Count; i++)
        {
            if (joinMessages[i].timer > 0)
            {
                joinMessages[i].timer -= Time.deltaTime;
            }
        }

    }
private void OnGUI()
    {
        for (int i = 0; i < joinMessages.Count; i++)
        {
            if (joinMessages[i].timer > 0)
            {
                GUI.backgroundColor = Color.black;
                GUI.Label(new Rect(5, Screen.height - 85 - 25 * i, 200, 500), joinMessages[i].message);
                GUI.skin.label.fontSize = 10;

            }
        }

    }
[PunRPC]

    public void SendMessageJoinedRoom(string feed)
    {
        JoinMessage m = new JoinMessage();
        m.message = feed;
        m.timer = 15.0f;
        
        Debug.Log(PhotonNetwork.NickName + " joined");
    }
this is my code
and this is the code when if it worked but it was never erased
public int index = -1;
    public string[] msgJoined;
    int NormalIndex;
private void OnGUI()
  {  
        GUILayout.BeginArea(new Rect(Screen.width - 85, 25, 200, 500));
        GUI.skin.label.fontSize = 10;
        foreach (string msg in msgJoined)
        {

            GUILayout.Label(msg);


        }
        GUILayout.EndArea();
       

    }
[PunRPC]

    public void SendMessageJoinedRoom(string feed)
    {
        index = index + 1;
        msgJoined[index] = feed;
        
        Debug.Log(PhotonNetwork.NickName + " joined");
    }