I just noticed this today. On various profiles are HTML code [like
on mine is ♦ which should make a diamond emoji] and those
have been working for a while. Today I was looking at someone's
profile who had the HTML code and emojis last time I saw their
profile, but now it's not working.

shows what it looks like currently,
instead of those codes being replaced with their respective
emojis/icons.
I don't know if it's just for me, but I checked it on my laptop &
mobile and the same problem occurs.