Threads are hosted on the instance that the magazine is on. I think instances viewing it also just make a copy?
You can check the @ to see the url for both users and magazines. I'm not fond of the fact that kbin often hides the @url for things. I'd much prefer to see it since it makes things feel bigger to me. @.chat@beehaw.org just ends up being shortened to @.chat lol. see? @chat@chat they are identical lmao. it's annoying.