I'm attempting to update some forms made in Classis Forms Designer into "Modern Forms"

There's an external javascript file which while easier to load in with Modern Forms is used to call a webservice to retrieve information on a people to pre-populate fields.

It seems that when the modern forms sticks the JavaScript into the sandbox it somehow also scrubs the origin from the call to the webservice. While the Service is set up to accept calls from the Forms Web Server, somehow the origin is missing and thus blocked by CORS on the webservice.

Is there any workaround for this?

(No, Turning off CORS on the webservice is not an option.)