Did you push the wheel on the right of rounded corners entry to open the settings (Configure)?
Edit:
I see your problem probably.
I just updated, the
kwin-effect-rounded-corners-git package got updated (along with kwin) and the effect disappeared!The reason most likely being:
So, I think a rebuild in chaotic-AUR is in order…
Maybe also for kwin-effects-forceblur?
Actually, if I may try to put my two cents in, in chaotic-AUR, I still see version 0.7.1.r11.g81fb4e0-1.5, while the last commit seems to me to be CI_PACKAGE_BUMP=0.7.1.r11.g81fb4e0-2/6, so either it hasn’t been deployed yet or something has gone wrong.
In-fact, rebuilding them both with paru worked, and now they are available again.