QGIS - connect to ArcGIS FeatureServer hosted behind Azure proxy

I am using the QGIS (v3.16.0) ArcGisFeatureServer tool in the Browser window to try and connect to the following ArcGIS Feature Server: https://gojdippmaps.azurewebsites.net/proxy.ashx?https://maps.gov.je/arcgis/rest/services/Historic_Buildings/Historic_Buildings/FeatureServer

Note that this server requires an http referrer, such as: https://www.gov.je//citizen/Planning/Pages/HistoricEnvironmentDetail.aspx

Note also that the host is gojdippmaps.azurewebsites.net and the https://maps.gov.je.. url is treated as a parameter in the query string (preceded by ? after the path /proxy.ashx).

If I add the url as shown above I get "Connection failed: Network error" from the ArcGisFeatureServer tool. Hovering over this yields the following message:

Error transferring https://gojdippmaps.azurewebsites.net/proxy.ashx?https://maps.gov.je/arcgis/rest/services/Historic_Buildings/Historic_Buildings/FeatureServer&f=json – server replied: Bad Request

This appears to be because QGIS is trying to add f=json as a second parameter to the query string (preceded by &). If I instead make the request in a web browser (using the referrer header above) but replace the & with ? the request is successful.

Question: Is it possible (using the ArcGisFeatureServer tool or otherwise) to connect to this server and add the layer it contains to a QGIS project?

I have no expertise in Azure-hosted web applications and this is the first time I’ve seen a proxied url in a query string like this treated as a parameter. It appears QGIS cannot correctly deal with this scenario.