Não estou conseguindo gerar uma chave publica com api no sandbox

Quanto tento gerar aparece este erro.

var options = new RestClientOptions("https://sandbox.api.pagseguro.com/public-keys");

            using (var client = new RestClient(options))
            {
                var request = new RestRequest("");
                request.AddHeader("accept", "application/json");
                request.AddHeader("Authorization", "Bearer 996B9A1207E04D0D82A3A9E0DDE03D5B");
                request.AddJsonBody("{\"type\":\"card\"}", false);
                var response = await client.PostAsync(request);      
                Result.Result = (string?)JObject.Parse(response.Content)["public_key"]; 
            }

Not found because of proxy error: Error: certificate has expired