Bootstrap 5 popover positioning problem (when located after a header)

Question

Can anyone explain why a popover within a container-fluid after a header element does not respect 'bottom' positioning?

Note that it does when one either removes the header OR converts the container to a regular non fluid variety (setting #main max-width to 100% on the regular container doesn't work either).

I definitely want a header and need the full width so neither of the above is a viable solution.

$(document).ready(function() {

  $('[data-bs-toggle="popover"]').popover({
    container: 'body'
  }).popover('show');
});

.container-fluid {
  background: pink;
}

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">

<header>
  <nav class="navbar navbar-expand">
    My header
  </nav>
</header>

<div id="main" class="container-fluid">
  <div class="row">
    <div class="col">
      Here's some left aligned stuff
    </div>
    <div class="col d-flex justify-content-end">
      <a href="" class="btn btn-primary" data-bs-toggle="popover" data-bs-animation="false" data-bs-html="true" data-bs-content="Hello <b>World</b>, it's good to be here!" data-bs-placement="bottom">My Button</a>
    </div>
  </div>
</div>

<footer class="footer">
  My Footer
</footer>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js" integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p" crossorigin="anonymous"></script>