Why does it only show a message for one player?

Question

Unity

For some reason, the message comes only to one user, and the second does not receive it

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Photon.Pun;
using Photon.Realtime;
using UnityEngine.UI;

public class Nick : MonoBehaviour,  IPunObservable
{
  private PhotonView photonView;
  public Text t;
  public InputField field;

  private string chat;

    public void OnPhotonSerializeView(PhotonStream stream, PhotonMessageInfo info)
    {
       if (stream.IsWriting)
       {
            stream.SendNext(chat);
       }
       else
       {
            chat = (string) stream.ReceiveNext();
       }         
    }

    private void Start()
    {
    	photonView = GetComponent<PhotonView>();
    }   

    private void Update(){
    	if (photonView.IsMine == false){
    		t.text = chat;
    		return;
    	}
    }

    public void ButtonSend(){
    	chat = field.text;
    	t.text = chat;
    }
}

Many thanks to anyone who can help!