How to display what's on signature field in PDF?

Question

As stated in the title, I am trying to print the submission into PDF file when I submit the webform. Everything is printed except the signature field. I have searched and searched and finally used
<td height="100">{{ webform_token('[webform_submission:values:director_approval:image:html]', webform_submission) }}</td>

based on https://www.drupal.org/project/webform/issues/3134568 and

<img src="{{ webform_token('[webform_submission:values:director_approval:url]', webform_submission) }}" /> inside the td tag, but none of them would print the signature, but instead, it crashes the entire twig template like

I really would like to ask your help to render the signature.

Here is the whole code of the highlighted part of the image:

<tr>
    <td height="100">{{ webform_token('[webform_submission:values:director_approval:image:html]', webform_submission) }}</td>
</tr>