This is just a boilerplate to save a bit of time with copy paste when needed

ShowClaimsPageRazor

@page "/Claims"
@inject AuthenticationStateProvider AuthState

    <AuthorizeView>
        <Authorized>
            <h2>
                Hello @Username,
                here's the list of your claims:
            </h2>
            <ul>
                @foreach (var claim in context.User.Claims)
                {
                    <li><b>@claim.Type</b>: @claim.Value</li>
                }
            </ul>
        </Authorized>
        <NotAuthorized>
            <p>I'm sorry, I can't display anything until you log in</p>
        </NotAuthorized>
    </AuthorizeView>

@code
{
    [CascadingParameter] Task<AuthenticationState> authenticationStateTask { get; set; }
    private string Username = "Anonymous User";

    protected override async Task OnInitializedAsync()
    {
        var authState = await authenticationStateTask;
        var user = authState.User;

        Username = user.Claims
            .Where(c => c.Type.Equals("[Claim that represents user's name in any context]"))
            .Select(c => c.Value)
            .FirstOrDefault() ?? string.Empty;

        await base.OnInitializedAsync();
    }
}