Scoped labels display incorrectly in email

Summary

Scoped labels are unreadable in some email clients. Tooltips are also incorrectly formatted.

Steps to reproduce

Use thunderbird, receive an email containing a reference to a scoped label.

You will notice that the label is unreadable (white on white):

Screenshot_2022-03-07_at_10.03.01

And that the tooltip includes HTML literals:

Screenshot_2022-03-07_at_10.05.30

Example Project

This happens on gitlab-org/gitlab>

Possible fixes

Review email templates and CSS