Issues label bug if use emoji(s)

Summary

On personal instance, I have a project with star(s) on it labels. Working fine on gitlab-ce-source 12.4.x. Broken since 12.5.x

Steps to reproduce

• Create label starting with one or more '⭐️'
• Use firefox on linux (ok, on windows / chromium)

Emoji itself seam not working on preview, image copy:

Example Project

• Example project/issue: ax10336/label-test#1

What is the current bug behavior?

• that:

What is the expected correct behavior?

• something like that:

Relevant logs and/or screenshots

• see first comment (sorry)

Output of checks

• This bug happens on GitLab.com, should be a regression:12.5 ?