There are too many horizontal lines in the search results. See discussion and mockups in the VDG forums: https://forum.kde.org/viewtopic.php?f=285&t=125740 and https://forum.kde.org/viewtopic.php?f=285&t=125552#p332312 Reproducible: Always
I love the images on the forum. I however, have to no idea how to implement this. It's certainly not trivial. Marking as CONFIRMED.
Plasma 5.6 has a cleaner look with separator lines only between different categories.