Actually there is something like that in the internationalised DNS standards (that is, internet domain names that look like .xn--xyz-abc sometimes and .日本 other

Actually there is something like that in the internationalised DNS standards (that is, internet domain names that look like .xn--xyz-abc sometimes and .日本 other times.) There's a blacklist of certain Unicode characters that are disallowed in domain names because they resemble more commonly used characters. See https://en.wikipedia.org/wiki/IDN_homograph_attack https://en.wikipedia.org/wiki/IDN_homograph_attack