NSwag: OAuth2 invalid redirection to localhost:3200 (SwaggerUi3)

When you switch from .UseSwaggerUi() to .UseSwaggerUi3() and try to use OAuth 2.0 Authorization in the Swagger Ui, the redirection after signing in (to e.g. Azure AD) always wants to go to localhost:3000.

So:

app.UseSwaggerUi(typeof(Startup).GetTypeInfo().Assembly, new SwaggerUiSettings()
    {
        OAuth2Client = new OAuth2ClientSettings
        {
            ClientId = clientId,
            ClientSecret = clientSecret,
            AppName = "App",
                Realm = realm,
                AdditionalQueryStringParameters =
                {
                    { "resource", clientId }
                }
           },
          DocumentProcessors =
          {
              new SecurityDefinitionAppender("oauth2", new SwaggerSecurityScheme
              {
                   Type = SwaggerSecuritySchemeType.OAuth2,
                   Description = "DocCheck",
                   Flow = SwaggerOAuth2Flow.Implicit,
                   AuthorizationUrl = authorizationUrl,
                   TokenUrl = tokenUrl,
               })
           },
           OperationProcessors =
           {
               new OperationSecurityScopeProcessor("oauth2")
           },
           DefaultPropertyNameHandling = PropertyNameHandling.CamelCase,
    });

works correctly.
If you change it to SwaggerUi3 and SwaggerUi3Settings without changing anything else, you always get redirected to localhost:3000 after signing in. I guess its hardcoded somewhere?