I read the thread, but I couldn't find anything helpful. All I saw was recommending `combiningchars`.
I was in part referring to the explanations of why it's so difficult to get this right.
By "I type an emoji" I mean I use the
emoji input on my Mac
Thanks. I'm not able to find the commit that affected this, but I can confirm it happens as you describe with the default MacOS zsh (5.9) but no longer happens with a build from the git head revision.
For the record it doesn't really work "right" in bash either, try backspacing to erase the emoji and watch bash get confused about the cursor position / contents of the input line. That's related to what Mikael mentions about reliable display.