[yreg]

It's unrelated to HN. Copy pasting 𝕏.com into the address bar still leads to x.com

related: https://en.wikipedia.org/wiki/IDN_homograph_attack

[mkl]

I already mentioned that, and it's not what they mean. Hover your mouse over a https://xn--971h.com link in a comment on HN and notice that it's pointing to https://x.com. This does seem to be an HN thing; see here: https://jsfiddle.net/rtfhejdy/