This KCM uses 32px icons in its list next to the description of the search plugins. The "Folder" plugin however uses a 48px icon and scales it to 32px resulting in a blurry icon. Reproducible: Always Steps to Reproduce: 1. Open System Settiungs 2. Go to the Search KCM 3. Change the 48px icon to something else, the plugin changes the icon Actual Results: The "Folder" plugin however uses a 48px icon and scales it to 32px. Expected Results: The "Folder" plugin uses a 32px icon.
Looks liked it was a cache issue. I've cleared the directories and reboot my system the icon is shown properly now.