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I know most of the shitposters in this thread are already aware, but for those who need to be spoonfed context:
If JPs use 卍 on twitter they usually mean the 3rd definition here. Similar connotation to "yabai", in that it can mean "awesome" or "oh no".
Presumably it was deleted because someone went "Suisei, westerners don't know better and just think swastika = nazi" and she went "Oh, I don't want people to get the wrong idea there."