Why does a keydown event is listened only once?

The following code (credit for user:hkotsubo) moves the user to another page if Alt+Shift+E are pressed together.

window.addEventListener('DOMContentLoaded', () => {
  let domain = window.location.host;
  let protocol = window.location.protocol;
  let h1 = document.querySelector("h1");

  window.addEventListener('keydown', function(event) {
      if (event.altKey && event.shiftKey && event.key === 'E') {
          window.location.href = `${protocol}//${domain}/index.php?title=${h1.innerText}&action=edit`;
      }
  });
});

I have the problem that the code can only run once.
Even if I run it from a user script manager so it's always in the background, still, I can use it to move a user to the edit page only once per page load, so if I want to use it again I have to refresh the page.

Why is this problem happening and how would you suggest to solve it?