I don't think that's about a JS library. Firefox bundles an emoji font that supports some things -- such as the flags -- that aren't supported by Segoe UI Emoji on Windows, so it has additional coverage for such character sequences.

That makes sense. I saw a failure to load a JS module in the console and assumed that was part of the problem.

There should not be any JS involved though, only a font able to render these grapheme clusters.

Do you see the US flag after "copy and paste this emoji" on https://emojipedia.org/flag-united-states/?

Reminds me of an image that renders differently on Macs (https://www.bleepingcomputer.com/news/technology/this-image-...), I bet it'd make for a fun conversation that could make the participants question their sanity. :-)

A whole lesson in Unicode in itself right there with your experience, haha!