NPC does not follow player movement

I'm making a multiplayer game, so the NPC will following the player when at a certain distance. Players are prefabs that cloned because its multiplayer, the NPC just follow the static position of the prefab (x y z=0) even the player is moving. Player prefab does not exist in the hierarchy its called when the game start, I don't know if it has any effect.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class npcAI : MonoBehaviour
 {
     Animator anim;
     public GameObject player;
 
     public GameObject GetPlayer()
     {
         return player;
     }
     // Start is called before the first frame update
     void Start()
     {
         anim = GetComponent<Animator>();
     }
 
     // Update is called once per frame
     void Update()
     {
         anim.SetFloat("distance", Vector3.Distance(transform.position, player.transform.position));
     }
 }
 

In the "player" reference I set the player prefab, what should I do to fix it