svelte – revealjs with markdown not showing

I have a svelte component that embed a revealjs:

<script>
  import { onMount } from 'svelte'
  import Reveal from 'reveal.js';
  import Markdown from 'reveal.js/plugin/markdown/markdown.esm.js';
  let deck = null

  onMount(()=>{
    deck = new Reveal({
      plugins: [Markdown],
    });
    deck.initialize({ embedded: true });
    })
</script>

<div class="reveal">
  <div class="slides">
        <section>Horizontal Slide</section>
    <section data-markdown  data-background-color="rgb(70, 70, 255)" data-separator="---">
  <textarea data-template>
    ## Slide 1
    A paragraph with some text and a [link](https://hakim.se).
    ---
    ## Slide 2
    ---
    ## Slide 3
  </textarea>
</section>
  </div>
</div>

everything is working, except for the markdown part.

the first slide is working like normal.

the second slide is there with background color, but nothing else.

the console did not show any error message at all. So I am not sure how to debug.

I did try to add the plugins into the initialize():

deck.initialize({ embedded: true, plugins: [Markdown]});

but still the empty.

How can I resolve this?