Inconsistent Emoji formatting

While viewing a room I noticed one of the members only displays the first emoji in their name when they send a message to the room.

This morning I managed to catch them submitting a reaction and when mousing over that, the full display name was rendered properly.

Then I managed to catch them typing and it seems that when rendering in the buffer, unicode emoji are followed by super wide spacing which makes their name disappear on the left.

Don't know how much of the following affects this but here goes:
Windows 11
WSL 2
Debian Bullseye
Basic Emacs install (apt-get install emacs)

So Emacs is running as a GUI app.