Saving behind HTTPS proxy fails

I am using an nginx as an HTTP and HTTPS proxy before xwiki that is listening on "localhost:8080". However when creating a new diagram when using the HTTPS URL I get an error that the diagram could not be saved. I see that this URL is called from my browser:

http://localhost:8080/xwiki/rest/jobstatus/refactoring/create/1554291908343-403?media=json

This is obviously wrong and will not work. The URL should have been something like:

https://wiki.my.domain/xwiki/rest/jobstatus/refactoring/create/1554291908343-403?media=json

Nginx sets the usual headers. It looks though like the Diagram application fails to deal with this setup.

Using HTTP through Nginx works by the way. The diagram is saved successfully.