Middle-Click to paste doesn't work in Snippets

Summary

I use Linux with FireFox.

When I go to make a snippet, I often copy code from my terminal by highlighting it and then middle-clicking to paste it somewhere else.

For the most part in FireFox, this works fine.

However, something about GitLab snippets prevent me from doing this. The middle-click doesn't register.

I can middle-click paste into the "Title" box, but not the content box where the snippet actually goes.

Steps to reproduce

Using Linux, highlight some text in a different program (or part of FireFox). Middle-click in the "Title" box of the new snippet page. Note that the data is pasted into the title. Middle-click in the content section of the snippet. Note nothing happens, or that the scroll up/down icon appears (normally middle clicking activates the scroller, but not in text inputs!).

Expected behavior

My data should be pasted to the snippet.

Actual behaviour

My data is not pasted to the snippet, and instead I get the normal middle-click scrolling behaviour for non-text-inputs.