Where is /login handled in ASP.Net Core Web API?

I have an ASP.NET Core Web API. When I set it up, I used the built-in ASP.NET Core identity stuff because that was fast and got me directly into writing the meat of the API functionality. Now I need to be able to log failed logins, but I can't see where to do this.

A class was created automatically at \Overrides\IdentityApiEndpointRouteBuilderExtensions.cs that contains a bunch of identity endpoints, including /login:

routeGroup.MapPost("/login", async Task<Results<Ok<AccessTokenResponse>, EmptyHttpResult, ProblemHttpResult>>
([FromBody] LoginRequest login, [FromQuery] bool? useCookies, [FromQuery] bool? useSessionCookies, [FromServices] IServiceProvider sp) =>
{
    var signInManager = sp.GetRequiredService<SignInManager<TUser>>();

    var useCookieScheme = (useCookies == true) || (useSessionCookies == true);
    var isPersistent = (useCookies == true) && (useSessionCookies != true);
    signInManager.AuthenticationScheme = useCookieScheme ? IdentityConstants.ApplicationScheme : IdentityConstants.BearerScheme;

    var result = await signInManager.PasswordSignInAsync(login.Email, login.Password, isPersistent, lockoutOnFailure: true);

    if (result.RequiresTwoFactor)
    {
        if (!string.IsNullOrEmpty(login.TwoFactorCode))
        {
            result = await signInManager.TwoFactorAuthenticatorSignInAsync(login.TwoFactorCode, isPersistent, rememberClient: isPersistent);
        }
        else if (!string.IsNullOrEmpty(login.TwoFactorRecoveryCode))
        {
            result = await signInManager.TwoFactorRecoveryCodeSignInAsync(login.TwoFactorRecoveryCode);
        }
    }

    if (!result.Succeeded)
    {
        return TypedResults.Problem(result.ToString(), statusCode: StatusCodes.Status401Unauthorized);
    }

    // The signInManager already produced the needed response in the form of a cookie or bearer token.
    return TypedResults.Empty;
});

In my Program.cs in the Main method, I have these lines:

builder.Services.AddAuthorization();
builder.Services.AddIdentityApiEndpoints<IdentityUser>().AddEntityFrameworkStores<DataContext>();

I can't hit breakpoints in that routeGroup.MapPost("/login". In fact, if I remove all of the code from that method, the login still works flawlessly. Obviously, this code is not handling logins.

Where can I find the code that handles these logins so that I can start logging failed logins?