Issues search bar shows duplicate labels that no longer exist

Hello everyone,

We encountered, what seems to be a visual bug in Gitlab web GUI, but are unsure of as how we should try to reproduce it.

When using the search bar in the Issues List we see a lot of duplicate labels that were defined in the Admin Area as a test and removed at some point later.

Once we filter for this label, no results show up.

This is a bit of an annoyance, since it clutters the labels list.

At first we thought, that this was caused by Issue 30390, but after confirming our gitlab version and going over the issue in a bit more detail, it does not seem to be so.

We are using GitLab Community Edition 13.10.2