utility.lookupinvite: default gdm avatar accuracy

src/modules/utility.js

@@ -528,7 +528,9 @@ lookupinvite.callback = async function (msg, line) {
             }`
           : "https://discord.com" +
             DEFAULT_GROUP_DM_AVATARS[
-              Number(invite.channel.id) % DEFAULT_GROUP_DM_AVATARS.length
+              (Math.floor(Number(invite.channel.id) / Math.pow(2, 22)) +
+                1420070400000) %
+                DEFAULT_GROUP_DM_AVATARS.length
             ],
       };
     } else if (invite.type == 2) {