Hi @cyber thank you for the additional details.
Apologies for the issue, that is very odd.
So the error always says "failed to fetch dynamically imported module" although with a different URL even after you deleted any and all Libraries or Preloaded JS?
And even in a newly created app after you deleted the app where the error messages started?
Can you used you browser inspector to check the 'Networking' tab to see if there are more details on the error in this console?
You may need to come into our office hours for live debugging, I haven't seen anything like this before 
I was hoping that by reversing anything you had done in terms of customizing the app would fix this, or by starting from a blank slate.