CORS error continues on node.js even after importing the cors package

I have included the cors package tries the res.header and still getting the cors error

Access to XMLHttpRequest at 'localhost:3000/auth' from origin 'http://localhost:4200' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, isolated-app, chrome-extension, chrome, https, chrome-untrusted.

I am running my angular project at localhost:4200 and the node server at 3000 here is the node code:

app.js

    require("./src/db/mySQLConnet");
    const express = require("express");
    const AllFunction = require("./src/routes/allFuntions");
    const cors = require("cors");
    const app = express();
    app.use((req, res, next) => {
      res.setHeader("Access-Control-Allow-Origin", "*"); 
      res.setHeader("Access-Control-Allow-Headers", "*");
      res.setHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE");
      console.log(req);
      next();
    });
    const port = 3000;
    app.use(cors());
    app.use(express.json());
    app.use(AllFunction);
    app.listen(port, () => {
      console.log("Server started on port 3000");
    });

the allFunctions.js file

    const express = require("express");
    const router = new express.Router();
    const db = require("../db/mySQLConnet");
    //Check User
    router.post("/auth", (req, res) => {
      let Username = req.body.username;
      let Password = req.body.password;
      let sql = "SELECT * FROM user WHERE username=? AND password=?";
      console.log("here");
      let query = db.query(sql, [Username, Password], (err, result) => {
        if (err) throw err;
        res.send(result);
      });
    });
    module.exports = router;

the mysqlConnect.js

    const mysql = require("mysql");
    const db = mysql.createConnection({
      host: "localhost",
      user: "root",
      password: "123456",
      database: "company", 
    });
    //Connect
    db.connect((err) => {
      if (err) {
        throw err;
      }
    console.log("Mysql Connected....");
    });
    module.exports = db;

My angular request is simple

    checkUser(body: any) {
        return this.http.post(`${this.API_URL}/auth`, body);
      }
    this.requestService.checkUser(this.loginFrom?.value).subscribe((res) => {
          console.log(res);
      });