mCaptcha/templates/panel/add-site-key/existing-level.html

<div class="sitekey-form__add-level-flex-container">
  <!-- insert Javascript for adding more levels as needed -->
  <label class="sitekey-form__label" for="level<.= level .>">Level <.= level .></label>
</div>

<input
  class="sitekey-form__input"
  type="number"
  name="level1"
  id="level<.= level .>"
  value=""
/>