

There are some other ways posted in the comments, but I used an Extension called Stylus and added the following to youtube.com:
@-moz-document url-prefix("https://www.youtube.com/") {
ytd-rich-item-renderer{
--ytd-rich-grid-items-per-row: 5;
}
}
Yea I would think anyone who has a workaround is keeping it quiet, otherwise it’ll get fixed before then. Then it would be harder to break it for gta.