The Twitch API uses a caching system that is only updated every few minutes. If you make requests within that update period, certain fields and endpoints won’t change even though you make a new request.
There is kind of a “hacky” way around this though to trick the API into giving you a brand new request instead of accessing the cache every time. All you need to do is add a query parameter with a random value every time a request is made, so something to the tune of this:
public new RestRequest Request(string endpoint, Method method)
{
RestRequest request = new RestRequest(endpoint, method);
request.AddHeader("Client-ID", g_client_id);
request.AddHeader("Authorization", "OAuth " + g_oauth_token);
request.AddQueryParameter("api_version", "5");
request.AddQueryParameter("no_ache", DateTime.Now.Ticks.ToString());
return request;
}