I’m going to guess something is not setup correctly, since parts of the widget (Request Camera Permissions and Scan an Image File buttons) are missing.
Make sure you have installed the widget according to the docs:
Command line access is not supported here, so you’ll need to run commands on your machine and upload resulting files over FTP
But it should be noted that the scanner widget appears to be rendered completely by the browser. So there is no way for us to affect that from the server/hosting side. The code on the codepen and on your website appears to be identical, so I have no idea why it doesn’t work. There are no errors reported on your site at all.
When I run a little test script to get camera permission, it does work correctly.
So I’m guessing the issue you’re having has something to do with the internals of the QR code library you’re using. But I have no experience with that library, so I cannot really help you with that.