Did you even check the links? Sure most codes are from twitter, but qute a few from other sources. And exept maby 1? all codes have been 1 or 2 klicks away from twitter, that they woud hide the last codes in some ubscure chinease website that only get 500 klicks a month is not likley.
From what I have seen most are hidden in images/gifs/videos.
Also, it is entirely possible that while I don't believe any have been found in live streams, that that is where they are.. I haven't had the time to watch the streams myself so I cannot verify one way or another... but...
Two old codes were found in Critical Role's little "commercial" about the game. but they were already found in different places, a little disappointing.