Fix thread member download on create (#2072)

Author: quinchs

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -2913,6 +2913,9 @@ internal void EnsureGatewayIntent(GatewayIntents intents)
             }
         }
 
+        internal bool HasGatewayIntent(GatewayIntents intents)
+            => _gatewayIntents.HasFlag(intents);
+
         private async Task GuildAvailableAsync(SocketGuild guild)
         {
             if (!guild.IsConnected)

src/Discord.Net.WebSocket/Entities/Channels/SocketTextChannel.cs

@@ -119,7 +119,8 @@ public virtual async Task<SocketThreadChannel> CreateThreadAsync(string name, Th
 
             var thread = (SocketThreadChannel)Guild.AddOrUpdateChannel(Discord.State, model);
 
-            await thread.DownloadUsersAsync();
+            if(Discord.AlwaysDownloadUsers && Discord.HasGatewayIntent(GatewayIntents.GuildMembers))
+                await thread.DownloadUsersAsync();
 
             return thread;
         }