mutter-rounded VS KDE-Rounded-Corners

Everything you need is under the install section

For rounded corners I've used Mutter Rounded which is basically a patched Mutter (Gnomes window manager)

Since OP doesn't answer I simply googled it and it seems like OP uses this project: https://github.com/yilozt/mutter-rounded

Good question. The dev himself has said he does use a certain patch in his build. See here.. However, I went inside the code and it appears that he first downloads the Mutter source from RPM (which does not have the performance patches, yet), builds a big "meta"-patch out of everything in the "patches" folder, and applies those changes on the downloaded mutter build. So to be safe, I downloaded 1877 and 2487 manually, and edited package.sh myself. Gnome runs significantly faster, with fewer dropped frames, especially in the overview and app menu. (1877 gave me a few quirks though so you might want to skip that.)

I believe the app launcher follow your current plasma style for corners. But for rounded corners on windows, this is what I currently use and it works very well. https://github.com/matinlotfali/KDE-Rounded-Corners

See here: https://github.com/matinlotfali/KDE-Rounded-Corners

You could use [this](https://github.com/matinlotfali/KDE-Rounded-Corners} desktop effect and set a border of 1-2 pixels.

Try one of these: https://github.com/khanhas/ShapeCorners https://github.com/matinlotfali/KDE-Rounded-Corners

I don't use Plasma but this should do the job for you

It looks like that repository is deprecated in favor of this one: https://github.com/matinlotfali/KDE-Rounded-Corners

Are you sure you didn't build https://github.com/matinlotfali/KDE-Rounded-Corners yesterday?