This script will revert all UI changes prior to late 2022 (which disables rounded corners on everything and reverts 2019-2022 backgrounds.)
< 脚本 YouTube - Revert UI changes before late-2022 (Non-Rounded Design) 的反馈
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