No, they base on Ubuntu LTS and that has an outdated and broken version of Plasma, just like Kubuntu has.
I only recommend to use Plasma on Fedora Kinoite as I dont know other OSses. But I assume Arch and Opensuse Tumbleweed are also okay.
KDE doesnt do stable releases, they release when it is ready. And distro maintainers would need to backport all the fixes in Plasma 6 to Plasma 5 and to my knowledge nobody does that.
Qt5 is also not supported anymore, so you are running a desktop that had backported fixes to Qt from the KDE team even before Plasma 6 came out.
Plasma 6 is way more robust than Plasma 5. It just works way better. I use it daily, and can really really recommend Fedora Kinoite.