Whats wrong with my code.? Please help

<?php

//Import the PHPMailer class into the global namespace
use PHPMailer\PHPMailer\PHPMailer;
require 'vendor/phpmailer/src/PHPMailer.php';
require 'vendor/phpmailer/src/Exception.php';
require 'vendor/phpmailer/src/SMTP.php';


if ($_SERVER["REQUEST_METHOD"] == "POST") {
      $name = trim(filter_input(INPUT_POST, "name", FILTER_SANITIZE_STRING));
      $email = trim(filter_input(INPUT_POST, "email", FILTER_SANITIZE_EMAIL));
      $details = trim(filter_input(INPUT_POST, "details", FILTER_SANITIZE_SPECIAL_CHARS));

      if ($name == "" || $email == "" || $details == "") {
        echo "Please fill in the required fields: Name, Email and Details";
        exit;
      }


      if ($_POST["address" != ""]) {
        echo "Bad form input";
        exit;
      }

      require("inc/phpmailer/class.phpmailer.php");


      if (!$mail::ValidateAddress($email)) {
        echo "Invalid Email Address";
        exit;
      }


      $email_body = "";
      $email_body .= "Name " . $name . "\n";
      $email_body .= "Email " . $email . "\n";
      $email_body .= "Details " . $details . "\n";

       // TO DO: Send email
      $mail = new PHPMailer;


      //Tell PHPMailer to use SMTP
      $mail->isSMTP();
      //Enable SMTP debugging
      // 0 = off (for production use)
      // 1 = client messages
      // 2 = client and server messages
      $mail->SMTPDebug = 2;
      //Set the hostname of the mail server
      $mail->Host = 'smtp.gmail.com';
      // use
      // $mail->Host = gethostbyname('smtp.gmail.com');
      // if your network does not support SMTP over IPv6
      //Set the SMTP port number - 587 for authenticated TLS, a.k.a. RFC4409 SMTP submission
      $mail->Port = 587;
      //Set the encryption system to use - ssl (deprecated) or tls
      $mail->SMTPSecure = 'tls';
      //Whether to use SMTP authentication
      $mail->SMTPAuth = true;
      //Username to use for SMTP authentication - use full email address for gmail
      $mail->Username = "sirajdevelopment123@gmail.com";
      //Password to use for SMTP authentication
      $mail->Password = "***************";

       //It's important not to use the submitter's address as the from address as it's forgery,
       //which will cause your messages to fail SPF checks.
       //Use an address in your own domain as the from address, put the submitter's address in a reply-to
       $mail->setFrom($email, $name);
       $mail->addAddress('sirajdevelopment123@gmail.com', 'Siraj Khan'); // Add a recipient

       $mail->isHTML(false);                                  // Set email format to HTML

       $mail->Subject = 'Personal Media Library suggestion from' . $name;
       $mail->Body = $email_body;

       if (!$mail->send()) {
           echo "Message could not be sent.";
           echo "Mailer Error: " . $mail->ErrorInfo;
           exit;
       }

       header("location:suggest.php?status=thanks");
}


$pageTitle = "Suggest a media Item";
$section = "suggest";

include('inc/header.php') ; ?>


<div class="section page">
  <div class="wrapper">
    <h1>Suggest a Media Item</h1>

    <?php if (isset($_GET["status"]) && $_GET["status"] == "thanks") {
      echo "<p>Thanks for the email. I will check out your suggestion shortly!</p>";
    } else { ?>

    <p>If you think there is something I am missing, let me know.! Complete the form to send me an email.</p>

    <form method="post" action="suggest.php">

      <table>
        <tr>
          <th><label for="name">Name</label></th>
          <td><input type="text" id="name" name="name"></td>
        </tr>
        <tr>
          <th><label for="email">Email</label></th>
          <td><input type="text" id="email" name="email"></td>
        </tr>
        <tr>
          <th><label for="details">Suggest Item Details</label></th>
          <td><textarea name="details" id="details"></textarea></td>
        </tr>
        <tr style="display:none">
          <th><label for="address">Address</label></th>
          <td><input type="text" id="address" name="address"/>
          <p>Please leave this field blank</p></td>
        </tr>

      </table>

      <input type="submit" value="Send" />

    </form>

  <?php } ?>

  </div>

</div>

<?php include('inc/footer.php'); ?>