I found this ctor:

public class MobileOtpService : IMobileOptService
{
    private readonly HttpClient _client;

    public MobileOtpService(HttpClient client) // How is this injected?
    {
        _client = client;
    }
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddScoped<IMobileOptService, MobileOtpService>();
        ...
        services.AddHttpClient();
    }
}

I can’t find any hard-coded instantiations of MobileOtpService, so it must just be using DI.

How is the HttpClient injected?

Does this happen automatically because of services.AddHttpClient()?

I can’t find any code that sets the BaseAddress etc.