Why isn't the form submitting only in the Safari browser (on iMac and iOS)?

Question

JavaScript

The form is not submitted in the Safari browser (on iMac and iOS), when submitting the form - the page just reloads. All other browsers are ok.
Google doesn't even help.

Here is the ajax script

//E-mail Ajax Send
  $("#callback").submit(function() {
    var th = $(this);
    $.ajax({
      type: "POST",
      url: "mail.php",
      data: th.serialize()
    }).done(function() {
      $(th).find(".success").addClass("active").css("display", "flex").hide().fadeIn();
      setTimeout(function() {
        $(th).find(".success").removeClass("active").fadeOut();
        th.trigger("reset");
      }, 4000);
    });
    return false;
  });

But the form itself

<form class="form-lease" id="callback">
                        <div class="success"><span>Спасибо за заявку!</span></div>

                        <!-- Hidden Required Fields -->
                        <input type="hidden" name="project_name" value="site">
                        <input type="hidden" name="admin_email" value="[email protected]">
                        <input type="hidden" name="form_subject" value="description">
                        <!-- END Hidden Required Fields -->

                        <div class="row">

                            <div class="col-sm-6 wow slideInLeft">
                                <label>
                                    <span>Ваше имя</span>
                                    <input type="text" name="Имя" required><br>
                                </label>

                                <label>
                                    <span>Телефон</span>
                                    <input type="text" name="Телефон" required>
                                </label>

                                <label>
                                    <span>E-mail</span>
                                    <input type="email" name="E-mail" required>
                                </label>
                            </div>

                            <div class="col-sm-6 wow slideInRight">
                                <label>
                                    <span>Сообщение</span>
                                    <textarea rows="5" name="Сообщение" required></textarea>
                                </label>

                                <button class="btn-sub" type="submit">Отправить</button>    
                            </div>

mail.php file:

<?php

$method = $_SERVER['REQUEST_METHOD'];

//Script Foreach
$c = true;
if ( $method === 'POST' ) {

  $project_name = trim($_POST["project_name"]);
  $admin_email  = trim($_POST["admin_email"]);
  $form_subject = trim($_POST["form_subject"]);

  foreach ( $_POST as $key => $value ) {
    if ( $value != "" && $key != "project_name" && $key != "admin_email" && $key != "form_subject" ) {
      $message .= "<b>" . $key . "</b>: " . $value . "<br>";
    }
  }
} else if ( $method === 'GET' ) {

  $project_name = trim($_GET["project_name"]);
  $admin_email  = trim($_GET["admin_email"]);
  $form_subject = trim($_GET["form_subject"]);

  foreach ( $_GET as $key => $value ) {
    if ( $value != "" && $key != "project_name" && $key != "admin_email" && $key != "form_subject" ) {
      $message .= "<b>" . $key . "</b>: " . $value . "<br>";
    }
  }
}

function adopt($text) {
  return '=?UTF-8?B?'.Base64_encode($text).'?=';
}

$headers = "MIME-Version: 1.0" . PHP_EOL .
"Content-Type: text/html; charset=utf-8" . PHP_EOL .
'From: '.adopt($project_name).' <'.$admin_email.'>' . PHP_EOL .
'Reply-To: '.$admin_email.'' . PHP_EOL;

mail($admin_email, adopt($form_subject), $message, $headers );

Answer 1

$("#callback").on('submit', function(e) {
  e.preventDefault();
});

Answer 2

All decided. There was a mismatch with another plugin.