As far as I know, the graphical representation of Unicode Emojis is up to the respective software to implement. That’s why the same Emoji looks different on each platform.
The problem with TeamSpeak 3 is that it dates back to a time when Emojis were not a thing yet. It therefore doesn’t include custom code for displaying Emojis and support for them merely slipped in unintentionally with a QT update.
TeamSpeak could patch in a custom emoji renderer with properly designed and positioned graphics but that would be a decent amount of work for a software which will soon be EOL.
