I will not claim to be an expert by any means in embedding, but the one this that did catch my eye was the JS file listed in the post. Between the two versions of Tableau Server slight changes to JS API file were made. Below is a link to the Accessing API page from our Knowledge Base. Note the differences between version 9.1 and 9.2. No guarantee this is the issue but it definitely worth taking a look into. Additionally I am attaching article about what is new the JS API that might be beneficial for investigating the issue as well.
JS API | Knowledge Base
JS What's New? | Knowledge Base
I believe the above information will at least get the wheels turning towards a resolution.