Those four are listed specially as having optional emoji presentation: https://unicode.org/emoji/charts/emoji-variants.html https://unicode.org/emoji/charts/emo

Those four are listed specially as having optional emoji presentation: https://unicode.org/emoji/charts/emoji-variants.html https://unicode.org/emoji/charts/emoji-variants.html These all have Emoji_Presentation=No as specified in emoji-data.txt, for precisely this reason (to avoid discrepancies in rendering), but most platforms don't respect these defaults, as it's common to get strings containing emoji from mobile devices, which usually default to emoji presentation. I talk about this a little in my recent "Text layout is a loose hierarchy of segmentation" blog post.