with org-html-html5-fancy is non-nil, images are exported with something
like this code:

<figure>
<p><img src="https://imgs.xkcd.com/comics/proof_2x.png" alt="proof_2x.png"
class="fragment (appear) visible current-fragment"
data-fragment-index="0"></p>
</figure>


At least in ox-reveal, this makes it quite difficult to address images
separately from text (e.g., to set the text-align property appropriately.
You can try this if you have ox-reveal installed with any simple image:
----------
* Test
[[https://imgs.xkcd.com/comics/proof_2x.png]]

--------
At least on my machine, the image won't be centered in the resultant slide,
and it will be hard to construct CSS to fix the issue.

Is there a strong reason to include the <p> tag? I've removed it from
org-html--wrap-image and haven't noticed any ill effects so far, but
haven't done much testing.