working on a cart app in a udemy course - the problem is when the quantity gets bought it supposed to make the button disabled but its not working, only showing the add to cart button without disabling it when quantity are zero data.countInStock seems not to be updating

import { Button } from 'react-bootstrap';
import { Card } from 'react-bootstrap';
import { Link } from 'react-router-dom';
import React, { useContext } from 'react';
import Rating from './Rating';
import axios from 'axios';
import { Store } from '../Store';

function Product(props){
 const {product} = props;

const {state , dispatch:ctxDispatch} = useContext(Store);
const {cart: {cartItems}} = state

const addToCartHandler = async (item )=>{
  const existItem = cartItems.find((x)=> x._id === product._id);
   const quantity = existItem ? existItem.quantity+1:1 ; 

  const {data} = await axios.get(`/api/products/${item._id}`);
  if(data.countInStock < quantity){
      window.alert('sorry product is out of stock')
      return;
  }
   ctxDispatch({
       type:'CART_ADD_ITEM' 
       , payload:{...item , quantity},
   });
  };
  

return(

    <Card>


    <Link to={`/product/${product.slug}`}> 
      <img src={product.image} className="card-img-top" alt={product.name} />
    </Link>
    <Card.Body>
    <Link to={`/product/${product.slug}`}>
        <Card.Title>{product.name}</Card.Title>
    </Link>
    <Rating rating={product.rating} numReviews={product.numReviews} />
    <Card.Text>${product.price}</Card.Text>

    {  product.countInStock === 0 ? (

      
      <Button  color="light" disabled={true} >  Out of stock</Button>
      
    ):(
      
      <Button onClick={() => addToCartHandler(product)}>Add to cart</Button>
    )}
  </Card.Body>
</Card>
)}

it's not showing the button out of stock when quantity gets used, What's wrong with the code? full code: https://github.com/basir/mern-amazona/commit/12e565bf6e1859b963729eaba46a5352962fe9e1

full code with backend : https://github.com/basir/mern-amazona/tree/12e565bf6e1859b963729eaba46a5352962fe9e1