Are you sure? When I type https://xn--971h.com in it doesn't work, but clicking the link in your comment does because HN has made the href x.com. The browser converts 饾晱.com to x.com before going there too. Moreover, X and 饾晱 are treated as equivalent characters in this context, so whois 饾晱.com looks up x.com, and 饾晱.com's punycode encoding is x.com: https://www.whatsmydns.net/idn-punycode-converter?q=%F0%9D%9...
whois xn--971h.com returns the same thing as an unregistered domain.