as reported in Vietnam.net, it's possible Steam has been taken down in Vietnam after local game developers complained about the scope and size of Steam's vast portfolio of games, claiming Vietnamese devs cannot compete with Steam's releases given they are subject to government approval and thousands of international games on Steam are not.
Citing it as "an injustice to domestic publishers", Vietnamese studios reportedly say that local game development "will die" if Steam is able to keep releasing games without the same government scrutiny as domestic games.