Regarding the blurry icons in alt tab, I think this is a general problem on Linux and not KDE specific. I had the same issue with certain icons in Cinnamon, and

Regarding the blurry icons in alt tab, I think this is a general problem on Linux and not KDE specific. I had the same issue with certain icons in Cinnamon, and the following steps fixed it for me: Find the desktop file, for Cinnamon they're stored in /usr/share/applications For the blurry icon, append to the end of the file (obviously replacing Audacity with the app name) StartupWMClass=Audacity