This script disables YouTube's new rounded corners (reverts back to the previous layout from 2021.)
< Отзив за YouTube - Non-Rounded Design
Same here. Looks like YT updated again.
But, this one does work https://greasyfork.org/en/scripts/459222-youtube-non-rounded-design-legacy-version due to lacks JavaScript ES11 support
Seems like the Subscribe button dissapeared again