It doesn't work on mobile Edge browser. However, it does work on mobile Firefox (desktop page). After trying to figure out what the problem was, I realized it was a browser issue, not a script issue.

I rarely use YouTube on mobile and if I do I just use the youtube app, so I didn't feel the need for it on mobile (I usually just use desktop firefox on Arch Linux).

I might be simplifying the code at some point or have it as a separate website or something, but nothing set in stone yet.