[taejo]

It's a sequence of Unicode characters that's supposed to render as the Welsh flag. The first character U+1F3F4 BLACK FLAG seems to be missing (at least when I copy and paste it); that's followed by "tag letters" from the U+E0061-U+E007A spelling "gbwls". See https://unicode.org/reports/tr51/#valid-emoji-tag-sequences

I think the BLACK FLAG is getting removed by HN's emoji filtering, but the modifier characters after it are remaining.

[mikestew]

Thanks for the explanation. On my phone, so tools for diagnosis are lacking, but it sounds like you might know your Unicode better than I do anyway. :-)