Explain the problem.

apple
: pomaceous

  fruit

results in fruit in a separate paragraph outside the definition list:

<dl>
<dt>apple</dt>
<dd>
pomaceous
</dd>
</dl>
<p>fruit</p>

This is inconsistent with 4-space separated version

apple
:   pomaceous

    fruit

and from unordered list, where the second paragraph is correctly placed inside the list item:

- pomaceous

  fruit

<ul>
<li><p>pomaceous</p>
<p>fruit</p></li>
</ul>

I can open PR later.

Pandoc version?

pandoc version 3.7.0.2 on try.pandoc.org

Using the defaultpandoc --from markdown --to html5 --no-highlight