ServicePointManager.Expect100Continue = true;
                ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
                ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls
                                                       | SecurityProtocolType.Tls11
                                                       | SecurityProtocolType.Tls12
                                                       | SecurityProtocolType.Ssl3
                                                       | (SecurityProtocolType)12288; // Tls13 = 12288

                var webRequest       = (HttpWebRequest)WebRequest.Create("https://shop.blackanddecker.ru/yandexmarket/index/bd");
                webRequest.Method    = "GET";
                webRequest.Accept    = "text/html, application/xhtml+xml, application/xml, gzip, deflate, br, application/x-rar-compressed, application/octet-stream, application/zip; q=0.9,image/webp,*/*;q=0.8";
                webRequest.UserAgent = "Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:77.0) Gecko/20100101 Firefox/77.0";
                webRequest.AddRange(0);

                webResponse = (HttpWebResponse)webRequest.GetResponse();
                responseStream = webResponse.GetResponseStream();

и на последней строке — тадааам:

Error: The request was aborted: Could not create SSL/TLS secure channel.

ЧЯДНТ? Фреймворки пробовал от 4.5 до 4.7.2