I’m Running latest Discourse [v1.9.0.beta16 +71] at the time of writing and the Issue persists in the About Group Input box in New Group Page.
When the Emoji Button is clicked, it renders something like this:
Steps to repro:
EDIT: Issue is specific to firefox (latest)
in the Admin Panel, Go to Groups Section, Click on New and Then Try adding emoji to the About Group Section.
I assume this is caused after the New Composer was rolled out and emoji palette was modified to work with it.