Blazor WASM - Spending a long time initially in Authorizing component - blazor-webassembly

Question

My Blazor WASM (hosted) app is spending quite a long time (~10s) in the authentication process when I open the webpage for the first time and eventually logs
info: Microsoft.AspNetCore.Authorization.DefaultAuthorizationService[2]
Authorization failed. These requirements were not met:
DenyAnonymousAuthorizationRequirement: Requires an authenticated user.
Afterwards, it continues to show all content which is not wrapped in an Authorized tag.
In App.razor I use the Authorizing component and it shows its content ("Determining session state...") for a long time until it continues (see App.razor below).
The authentication in my app happens through an endpoint /authentication/login which forwards the user to Auth0 as identity provider using the
<RemoteAuthenticatorView Action="#Action">
component and the configuration in Program.cs
builder.Services.AddOidcAuthentication(options =>
{
builder.Configuration.Bind("Auth0", options.ProviderOptions);
options.ProviderOptions.ResponseType = "code";
options.ProviderOptions.AdditionalProviderParameters.Add(
"audience", builder.Configuration["Auth0:Audience"]);
});
App.razor
<CascadingAuthenticationState>
<Router AppAssembly="#typeof(App).Assembly">
<Found Context="routeData">
<AuthorizeRouteView RouteData="#routeData" DefaultLayout="#typeof(MainLayout)">
<Authorizing>
<p>Determining session state, please wait...</p>
</Authorizing>
<NotAuthorized>
<h1>Sorry</h1>
<p>You are not authorized to view this page</p>
</NotAuthorized>
</AuthorizeRouteView>
<FocusOnNavigate RouteData="#routeData" Selector="h1"/>
</Found>
<NotFound>
<PageTitle>Not found</PageTitle>
<LayoutView Layout="#typeof(MainLayout)">
<p role="alert">Sorry, there's nothing at this address.</p>
</LayoutView>
</NotFound>
</Router>
</CascadingAuthenticationState>