Grafana - Graph picture URL not correct

Hey there, I’m stuck at finding a Solution with the Grafana module and the pictures of the graphs it gives out.
I have Icinga running on the same server as a Grafana docker image and the image renderer and Icinga and grafana are accessible over FQDN and I configured the Grafana Module to use the indirectProxy to get the Images.
Getting those Images works fine but the URL the Module uses in the checks pages to show those graphs uses the internal IP of the Icinga Server and not the FQDN and I can’t for the life of me find out where this URL to the pictures gets generated and where it pulls the IP from.

So this is what I get:

but should be:


If I correct the URL how I want to have it it actually works, too and shows the correct image, I just get the wrong URL from the module.

Google and searching on here did not help but maybe someone can help me or knows what I’m missing or doing wrong?