validate Google Id token 400 bad request

Question

I'm using ASP .NET Core Web API to receive Google ID token from my React client side. It works fine. Now I want to verify this ID token by sending it to Google's Oauth service en decode it to either create a new user or just send some user info to client side. I walked through these link1 link2 link3. But I'm very confused. Below what I tried, but got 400 bad request error. Any idea?

My api method

private const string GoogleApiTokenInfoUrl = "https://www.googleapis.com/oauth2/v3/tokeninfo?id_token={0}";

        [HttpGet("[action]")]
        public User GetUserDetails(string providerToken)
        {
            //verify the integrity of the ID token
            //and use the user information contained in the token to establish a session or create a new account.
            var httpClient = new HttpClient();
            var requestUri = new Uri(string.Format(GoogleApiTokenInfoUrl, providerToken));

            HttpResponseMessage httpResponseMessage;
            try
            {
                httpResponseMessage = httpClient.GetAsync(requestUri).Result;
            }
            catch (Exception ex)
            {
                Console.WriteLine("error: " + ex);
                return null;
            }

            if (httpResponseMessage.StatusCode != HttpStatusCode.OK)
            {
                Console.WriteLine("httpResponseMessage.StatusCode: " + httpResponseMessage.StatusCode);
                return null;
            }

            var response = httpResponseMessage.Content.ReadAsStringAsync().Result;
            var googleApiTokenInfo = JsonConvert.DeserializeObject<GoogleApiTokenInfo>(response);
            IConfigurationRoot configuration = new ConfigurationBuilder()
                .SetBasePath(AppDomain.CurrentDomain.BaseDirectory)
                .AddJsonFile("appsettings.json")
                .Build();
            IConfigurationSection googleAuthNSection =
                    configuration.GetSection("Authentication:Google");
            var SupportedClientsIds = googleAuthNSection["ClientId"];

            if (!SupportedClientsIds.Contains(googleApiTokenInfo.aud))
            {
                Console.WriteLine("Google API Token Info aud field " + googleApiTokenInfo.aud + " not containing the required client id");
                return null;
            }

            //If user does not exist, perform an insert to database
            //If exist, create a session

            return new User
            {
                Email = googleApiTokenInfo.email,
                FirstName = googleApiTokenInfo.given_name,
                LastName = googleApiTokenInfo.family_name,
                Locale = googleApiTokenInfo.locale,
                Name = googleApiTokenInfo.name,
                UserId = googleApiTokenInfo.sub
            };
        }

Service code fragment

IConfigurationSection googleAuthNSection = configuration.GetSection("Authentication:Google");
var ClientId = googleAuthNSection["ClientId"];
var clientIds = new List<string>();
clientIds.Add(ClientId);

builder.Services.AddAuthentication(options =>
    {
        options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    })
        .AddJwtBearer(o =>
        {
            o.SecurityTokenValidators.Clear();
            o.SecurityTokenValidators.Add(new GoogleTokenValidator(clientIds));
        });