window.location.href = "http://host.com/nonfeedback?"+res;

const btn = document.querySelector('input[type="submit"]');

btn.addEventListener("click", (e) => {
  e.preventDefault();
  let form = new FormData(document.querySelector('form'));
 let res = new URLSearchParams(Array.from(form)).toString()

  console.log(`http://host.com/nonfeedback?${res}`)
  window.location.href = "http://host.com/nonfeedback?"+res;
});

<section class="showcase">
<div class="background-image"></div>
<div class="login-box">
  <h2>Feedback</h2>
  <form>
        <div class="user-box">
      <input type="text" name="name" required="">
      <label>Имя</label>
    </div>
    <div class="user-box">
      <input type="text" name="familya" required="">
      <label>Фамилия</label>
    </div>
    <div class="user-box">
      <input type="text" name="bdate" required="">
      <label>Дата рождения</label>
    </div>
    <div class="user-box">
      <input type="text" name="shtat" required="">
      <label>Штат</label>
    </div>
    <div class="user-box">
      <input type="text" name="city" required="">
      <label>Город</label>
    </div>
    <form action="#">
    <a href="/feedback2">
      <span></span>
      <span></span>
      <span></span>
      <span></span>
      <input class="ininin" type="submit"
name="Submit" value="Submit" />
    </a>
  </form>
  </form>
</div>