FitVid not working for iframes on particular theme install

I am using FitVid in my theme and all is well except for a specific site that was migrated from Drupal. FitVid works fine with objects and embeds but not iframes, and only on this particular site. The only difference I can find is that a random <noscript> is inserted after the iframe.

Here is an example of the non working iframe on the problematic site: https://wp.alimomeni.net/project/animal-warmth-no-64/

And here is an example with a different database where no shows up: https://wpfolio.notlaura.com/project/pollen-from-hazelnut/

Why is FitVid not working for iframes that particular site install? I am concerned there is an issue with the database itself as the content was pretty messy after the initial migration and I haven’t been able to replicate the issue anywhere else.

Any help greatly appreciated!

P.S. I have tried other responsive video plugins and my own jQuery to wrap the iframes.