Using RemoteAuthenticatorView OnLogInSucceeded gives a second AzureAD login dialog box

Well thanks to Raymond, I was also sent i a good direction, and made a component to load this type of data. I had to combine the event and loading when the component initializes. I still feel like M$ should and probobly will find a better way to do this.

For this application I use Azure B2C to auth, and I'm using redirect instead of popup. When I initialize the userstate, I call my api which gets the user profile, or creates one if it's a new user.

InitialDataLoader.razor

@implements IDisposable
@inject NavigationManager _navigationManager
@inject UserState _userState
@inject AuthenticationStateProvider _authenticationStateProvider

@ChildContent

@code {
    [Parameter]
    public RenderFragment ChildContent { get; set; }

    // The event can trigger multiple times when being redirected from the Authentication page to wherever you're going.
    // So we use this to check.
    public bool hasRunInit;

    protected override async Task OnInitializedAsync()
    {
        Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnInitializedAsync -> " + _navigationManager.Uri);

        // This component is already loaded and initialized on the Authentication page, so we have to subscribe to this event to
        // check when the user bounces back from Azure B2C and gets logged in. In that case, we do the initial load in on the event
        _authenticationStateProvider.AuthenticationStateChanged += this.OnAuthenticationStateChanged;


        // If the user is authenticated and reloads the page in the browser, the event won't trigger so we can do the initial load here.
        var user = (await _authenticationStateProvider.GetAuthenticationStateAsync()).User;
        Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnInitializedAsync -> IsUserAuthenticated: " + user.Identity.IsAuthenticated);
        Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnInitializedAsync -> IsStateInitialized: " + _userState.IsInitialized);

        if (user.Identity.IsAuthenticated && !_userState.IsInitialized)
        {
            hasRunInit = true;
            Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnInitializedAsync -> InitUser");
            await _userState.InitializeAsync(this);
        }
    }

    void IDisposable.Dispose()
    {
        _authenticationStateProvider.AuthenticationStateChanged -= this.OnAuthenticationStateChanged;
    }

    private async void OnAuthenticationStateChanged(Task<AuthenticationState> task)
    {
        Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnAuthenticationStateChanged -> " + _navigationManager.Uri);

        var user = (await task).User;
        Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnAuthenticationStateChanged -> IsUserAuthenticated: " + user.Identity.IsAuthenticated);
        Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnAuthenticationStateChanged -> IsStateInitialized: " + _userState.IsInitialized);

        if (user.Identity.IsAuthenticated && !_userState.IsInitialized)
        {
            if (!hasRunInit)
            {
                hasRunInit = true;

                Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " CascadingAppStateProvider -> OnInitializedAsync -> InitUser");
                await _userState.InitializeAsync(this);
            }
            else
            {
                Console.WriteLine(DateTime.Now.ToString("hh:mm:ss:fff") + " InitialDataLoader -> OnInitializedAsync -> Init has already been triggered!");
            }
        }
    }
}

App.razor

<CascadingAuthenticationState>

    <InitialDataLoader>

        <Router AppAssembly="@typeof(Program).Assembly">
            <Found Context="routeData">
                <AuthorizeRouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)">
                    <Authorizing>
                        ------------- Authorizing.. ------------------
                    </Authorizing>
                    <NotAuthorized>
                        @if (!context.User.Identity.IsAuthenticated)
                        {
                            <RedirectToLogin />
                        }
                        else
                        {
                            <p>You are not authorized to access this resource.</p>
                        }
                    </NotAuthorized>
                </AuthorizeRouteView>
            </Found>
            <NotFound>
                <LayoutView Layout="@typeof(MainLayout)">
                    <p>Sorry, there's nothing at this address.</p>
                </LayoutView>
            </NotFound>
        </Router>

    </InitialDataLoader>

</CascadingAuthenticationState>

When the user bounces back from the gateway, the component initializes before the application authenticates the user. Then the event triggers twice, once for the authentication page, and once for whatever page your are viewing.

Thanks to Zack Blazor Webassembly Authenticated Event, I was sent in a good direction and read Microsoft pages on AuthenticationStateChanged Event. It also simplified my code since I now have the retrival of UserProfile, in the UserProfile component than Authentication.razor.

@inject AuthenticationStateProvider AuthenticationStateProvider

private void OnAuthenticationStateChanged(Task<AuthenticationState> task)
{
    if(task.IsCompletedSuccessfully)
    {
        GetUserProfile();
    }
}

Not sure if this is "the final code", but it sure works and seems to me like a plausable way to go.