Почему ошибка data.forEach is not a function?

$(document).ready(function() {
    $("#clientType").keyup(function() {
      var inputVal = $(this).val();
      if (inputVal.length === 0) {
        $("#suggesstion-box").hide();
      }
      if (inputVal.length < 2) {
        $("#fio").attr("autocomplete", "off");
      }
      if (inputVal.length > 2) {
        $("#fio").attr("autocomplete", "on");
        $.ajax({
          type: "POST",
          url: "/vipapi/orders_search_by_fio_auto",
          data: 'fio=' + inputVal,
          beforeSend: function() {
            $("#fioEKB").css("background", "#FFF url(../../../assets/oc/dist/img/giphy.gif) no-repeat 165px");
          },
          success: function(data) {
            let box = $("#suggesstion-box");
            box.show();
            box.empty();
            data.forEach(function (item) {
              $("#suggesstion-box").append(
                '<ul class="my-orders">' +
                    '<li>' + item.fio + '</li>' +
                    '<li>' + item.card_type + '</li>' +
                    '<li><span class='+ item.package.name +'>' + item.package.name + '</span></li>' +
                '</ul>'
              );
            });
          }
        });
      }
    });