Sections wrapped in a shortcode do not appear in the TOC

Using a modified version of this in 2021 (Hugo has built in functions which do most of the work)

{{ $headers := findRE "<h[2].*?>(.|\n])+?</h[2]>" .Content   }}
{{ if and (ge (len $headers) 1) (ne $.Params.toc "none") }}
  <ul class="menu-list">
    {{ range $headers }}
      {{ $header := . | plainify | htmlUnescape }}
      <li><a href='#{{ $header | anchorize }}'>{{ $header }}</a></li>
    {{ end }}
  </ul>
{{ end }}

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