When I make an ajax request, I get an Uncaught InternalError: too much recursion error. Why might this be happening?

Question

AJAX

jquery code:

function follow() {
   const followBtn = $('.mypage__follow');

   followBtn.click(function () {
      $.ajax({
         type: 'POST',
         url: 'php-scripts/my-pageHandler.php',
         dataType: 'html',
         data: {
            followBtn: followBtn
         },
         success: function (data) {
            alert(data);
         }
      });
   });
}

PHP data handler code:

function follow()
{
   if (isset($_POST['followBtn'])) {
      echo 'Работает';
   }
}

It seems to me that there is no mistake here.