Data not transfering from Ajax to php to mail

I followed this tutorial : https://www.youtube.com/watch?v=DKq1n-awLcw
On how to implement a working contact form in my website.

Everything went fine, until I sent the first test mails and discovered that the mails are indeed sent, but without any informations : Empty mail received.

I'm not an expert in jquery or php, but I get how it works, and I can't seem to find why it is not working as intended.

I tried to tweek some variables here and there, but without any results.

Here is the HTML :

<form id="contactform" class="form-element" action="php/contact.php" method="post">
          
                    <label class="form-field">
                        <span>Name</span>
                        <input id="name" class="form-component" type="text" name="name" autocomplete="off" required>
                    </label>
            
                    <label class="form-field">
                        <span>Email</span>
                        <input id="email" class="form-component" type="email" name="email" autocomplete="off" required>
                    </label>
            
                    <label class="form-field">
                        <span>Subject</span>
                        <input id="subject" class="form-component" type="text" name="subjects" autocomplete="off" required>
                    </label>
            
                    <label class="form-field">
                        <span>Message</span>
                        <textarea id="message" class="form-text-area" name="message" autocomplete="off" required></textarea>
                    </label>
            
                    <div class="form-field">
                        <button class="form-submit" type="button" onclick="sendEmail()" value="Send an email.">Submit</button>
                    </div>
                </form>

Here the script :

<script type="text/javascript">
        function sendEmail(){
            var name = $("#name");
            var email = $("#email");
            var subject = $("#subject");
            var message = $("#message");

            if(isNotEmpty(name) && isNotEmpty(email) && isNotEmpty(subject) && isNotEmpty(message)){
                $.ajax({
                    url: 'php/contact.php',
                    method: 'POST',
                    dataType: 'json',
                    data:{
                        name: name.val(),
                        email: email.val(),
                        subject: subject.val(),
                        message: message.val() 
                    }, success: function(response){
                        $('#contactform')[0].reset();
                        $('.confirm-title').text("Message sent successfully!");
                    }
                });
            }
        }

        function isNotEmpty(caller){
            if(caller.val()=="") {
                caller.css('border', '1px solid red');
                return false;
            }
            else {
                caller.css('border', '');
                return true;
            }
        }
    </script>

And finaly here is the PHP document :

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;
use PHPMailer\PHPMailer\SMTP;

if(isset($_POST['name']) &&  isset($_POST['email'])){
    $name               =   $POST['name'];
    $email              =   $POST['email'];
    $subject            =   $POST['subject'];
    $message            =   $POST['message'];

    require_once $_SERVER['DOCUMENT_ROOT']."/php/includes/phpmailer/Exception.php";
    require_once $_SERVER['DOCUMENT_ROOT']."/php/includes/phpmailer/PHPMailer.php";
    require_once $_SERVER['DOCUMENT_ROOT']."/php/includes/phpmailer/SMTP.php";

    $mail = new PHPMailer();

    // SMTP Settings
    $mail->isSMTP();
    $mail->Host         =   "secret";
    $mail->SMTPAuth     =   true;
    $mail->Username     =   'secret';
    $mail->Password     =   'secret';
    $mail->Port         =   secret;
    $mail->SMTPSecure   =   "ssl";

    // Email settings
    $mail->isHTML(true);
    $mail->setFrom($email, $name);
    $mail->addAddress("secret");
    $mail->Subject      =   ("$email ($subject)");

    $MailBody           =   "From: ".$name."<br>";
    $MailBody           .=   "Email: ".$email."<br>";
    $MailBody           .=   "Message: ".$message."<br>";

    $mail->Body         =   $MailBody;

    if($mail->send()){
        $status = "success";
        $response = "Email is sent !";
    }
    else {
        $status = "failed";
        $response = "Something is wrong: <br>".$mail->ErrorInfo;
    }

    exit(json_encode(array("status" => $status, "response" => $response)));
}

I do receive the "Message sent successfully!" message on the website.

I already checked the "Transfer data from Ajax to php" post, and everything seems to be fine so..

You are not correctly collecting the values ​​of $_POST

$name               =   $POST['name'];
$email              =   $POST['email'];
$subject            =   $POST['subject'];
$message            =   $POST['message'];

try this way

$name               =   $_POST['name'];
$email              =   $_POST['email'];
$subject            =   $_POST['subject'];
$message            =   $_POST['message'];