Has anyone found a way around the Gutenberg HTML block changing HTML code when saved?

I the following AMP code that I need to insert:

<amp-iframe sandbox='allow-scripts allow-same-origin' layout=responsive resizable noloading src='/visualisation/456626/embed?auto=1' width=400 height=300>
<amp-img layout=fixed height=64 width=64 src='/resources/bosh.svg' placeholder style='margin: auto'></amp-img>
<div overflow></div></amp-iframe><p>
<a href='/visualisation/456626/?utm_source=embed&utm_campaign=visualisation/456626'>
<amp-img layout=fixed height=16 width=105 src='/resources/made_with_flourish.svg' alt='Made with Flourish'></amp-img></a></p>

But when I save it changes the amp-iframe and amp-img tags to amp -iframe and amp -img and breaks the code.