PHP CRUD data not posting even after db connection successful

I developed the create function for my PHP CRUD, the database connection is successful, but when I post the data, it doesn’t do anything. It should either say that the data is posted successfully or that there is an error.

I have two pages:

connect.php:

<?php 
$con = new mysqli('localhost', 'root', '', 'crudoperation');

if(!$con){
    die(mysqli_error($con));
}else{
    echo 'database connection successfully established';
}
?>

and user.php

<?php 
include 'connect.php';

if (isset($_POST['submit'])){ // si on appuye sur submit, poster tous les champs
    $name=$_POST['name'];
    $email=$_POST['email'];
    $mobile=$_POST['mobile'];
    $password=$_POST['password'];

    $sql="insert into `crud` (name, email, mobile, password)
    values('$name','$email','$mobile','$password')";
    $result=mysqli_query($con, $sql);
    if($result){
        echo "Data inserted successfully";
    }else{
        die(mysqli_error($con));
    }
}
?>

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>CRUD PHP</title>
    <link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-QWTKZyjpPEjISv5WaRU9OFeRpok6YctnYmDr5pNlyT2bRjXh0JMhjY6hW+ALEwIH" crossorigin="anonymous">
  </head>
  <body>
    <div class="container my-5">
        <form method="post">
            <div class="mb-3">
                <label>Name</label>
                <input type="text" class="form-control" placeholder="Enter your name" name="name" autocomplete="off">
            </div>
            <div class="mb-3">
                <label>Email</label>
                <input type="email" class="form-control" placeholder="Enter your email" name="email" autocomplete="off">
            </div>
            <div class="mb-3">
                <label>Mobile</label>
                <input type="text" class="form-control" placeholder="Enter your mobile number" name="mobile" autocomplete="off">
            </div>
            <div class="mb-3">
                <label>Password</label>
                <input type="password" class="form-control" placeholder="Enter your password" name="password" autocomplete="off">
            </div>
            <button type="submit" class="btn btn-primary">Submit</button>
        </form>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js" integrity="sha384-YvpcrYf0tY3lHB60NNkmXc5s9fDVZLESaAA55NDzOxhy9GkcIdslK1eN7N6jIeHz" crossorigin="anonymous"></script>
    <script src="https://cdn.jsdelivr.net/npm/@popperjs/[email protected]/dist/umd/popper.min.js" integrity="sha384-I7E8VVD/ismYTF4hNIPjVp/Zjvgyol6VFvRkX/vR+Vc4jQkC+hVqc2pM8ODewa9r" crossorigin="anonymous"></script>
    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.min.js" integrity="sha384-0pUGZvbkm6XF6gxjEnlmuGrJXVbNuzT9qBBavbLwCsOGabYfZo0T0to5eqruptLy" crossorigin="anonymous"></script>
  </body>
</html>

What can be the problem ?

I removed the name="submit" I previously had and instead of showing me a white screen, it showed me the same forms as before submitting.