So i've been able to reproduce this issue, I have done some research and what I understood is the problem comes from the length of Request-URI.
And here is somebody that proposed a workaround for this.
And here is blogpost that explains this workaround in details.
Furthermore I will create an issue in our issue tracker and link this thread to it.
Also I recommend you to check this thread as it seems a related issue.
Prismic preview not working (414 Request-URI Too Large – graphql queries too long)
Best,
Fares