How to embed Gmail markup in SendGrid dynamic templates

Question

I'm trying to embed email markup for Gmail, especially LodgingReservation schema in a SendGrid dynamic template, but cannot make it work. I already enabled SendGrid automatic security, so DKIM and SPF should be enabled for my account. Also, I'm testing with an email address which is the sender and the recipient at the same time for the testing purpose. So the requirements to test email markup should be met.

I understand that most email clients don't support tag for security reasons, so the only choice left for me may be Microdata. However, when I save the example in a SendGrid Code block, it removes itemprop or other attributes from the template.

This is what I get after saving the hotel reservation example in SendGrid Code

<div itemscope="">
  <meta content="abc456">
  <link href="http://schema.org/Confirmed">
  <div itemscope="">
    <meta content="John Smith">
  </div>
  <div itemscope="">
    <meta content="Hilton San Francisco Union Square">
    <div itemscope="">
      <meta content="333 O'Farrell St">
      <meta content="San Francisco">
      <meta content="CA">
      <meta content="94102">
      <meta content="US">
    </div>
    <meta content="415-771-1400">
  </div>
  <meta content="2027-04-11T16:00:00-08:00">
  <meta content="2027-04-13T11:00:00-08:00">
</div>

Can you please guide me on how to implement the hotel-reservation-type Gmail actions using SendGrid dynamic templates, or tell me what I'm missing?