WPF WebView2 - Cannot set "referer" header

Question

I'm trying to automate logging in to a website by posting the username and password throug a request. But i get an error from the website:

    { "detail": "CSRF Failed: Referer checking failed - no Referer." }

When adding a header like:

Dim request = MyWebview2.CoreWebView2.Environment.CreateWebResourceRequest("https://example.com/auth/login/", "POST", postDataStream, "Referer: https://example.com/auth/login/")
MyWebview2.CoreWebView2.NavigateWithWebResourceRequest(request)

or with

request.Headers.SetHeader("Content-Type", "application/json")
request.Headers.SetHeader("Referer", "https://example.com/auth/login/") 
MyWebview2.CoreWebView2.NavigateWithWebResourceRequest(request)

i still get the above 'no Referer"-error.

When I check with Developer Tools I indeed see the WebView doesn't send along the referer with the request. Anything other in the header will be added to the request:

request.Headers.SetHeader("foo", "bar")

Am I not allowed to "fake" the referer? In Postman I can set the referer without problems and login automated.