@jarek In my opinion the best GNU/Linux distro with KDE Plasma is openSUSE Tumbleweed. It has KDE software well integrated and as it is a rolling release it has latest releases quickly. And it heavily uses QA so they test packages before being released into repositories so it is also one of the most stable rolling release distros. And if despite this something goes wring there is BTRFS snappshoting integrated into package management and GRUB, so it is easy to revert to a working one