So this favicon seems to have inverted colours
This page should have the favicon, I had to use the built in php -S server to see it here since I have no idea how paths work besides hrefs lol.
Most other sites seem unaffected.
The issue is really on this project yt2009 which a custom frontend for YouTube that uses real archives and such (doesn't matter much).
On the top (FireFox) it is Red, on the bottom it is Blue