well being that HK and China are in a complicated spot it would make sense. China asserts that HK is under china rule, where HK doesn't really believe that.
Second I'm not an expert on the chinese internet, but I'd bet anything being hosted to china probably has more restrictions and steps than you setting up a server in your basement.
Now why to the site not being up while that occurs is up for debate, but why the site is not up isn't really important since we know the company is still working their plan in terms of swap stations
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