After digging through the issue I had finally found a solution:

  <script>
window.onbeforeunload = function (e) {
  const data = {
    userId: localStorage.getItem("outside"),
  }
  console.log("looog", data);
  // alert("IUIUIU")
  fetch("API_URL_ENDS_THE_SESSION", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify(data),
  })

  e = e || window.event;

  // // For IE and Firefox prior to version 4
  if (e) {
    e.returnValue = 'Sure?';
  }

  // // For Safari
  return 'Sure?';
}