Plasma 6 landed on Arch main... and I'm not sure what to make of it, just yet.
My panels were pretty much broken after the upgrade, but resetting them to defaults seemed to do the trick.
The HDR support seems a bit weird, as all SDR apps now look completely washed out. Probably just a setting I need to tweak, tho.
Other than that, it's been a lot smoother than the 4->5 and (especially) 3->4 major version upgrades.
Good job, KDE devs.