Thanks @cenguidanos, this is a bug, we’ll look into it.
There is a workaround - if you remove this tag:
<script src="https://anvil.works/embed.js" async></script>
and set the height of the IFrame explicitly (using whatever height works well for your app):
<iframe data-anvil-embed style="height: 560px" src="https://S2K6LRFPR6O94VOS.anvil.app/MK3KY4PVWRTEIRM2BGH3MSNS" ></iframe>
Then the infinite expansion won’t happen. The problem is with the script.