At present the Animated Heading generates the before and after text as html and it's ok. However the Changing text generates by JS.
The code looks like this
<h2 class="bde-animated-heading__text">
<span>This is</span>
<span class="bde-animated-heading__wrapper"></span>
<span>stuff.</span>
</h2>
Where bde-animated-heading__wrapper changes by JS dynamically.
It's bad for SEO because there are no Changing texts in html and search engines can't see them.
So this element is absolutely not suitable for use as headings.
Look at the same Elementor Pro widget. There is no such issue.