As someone who has extensively used both Cinnamon and Plasma: I find Plasma a lot less polished, by a huge margin. Not only do settings have unusual defaults and are located in places you wouldn’t expect, it also often has desktop-breaking bugs out of nowhere even in stable versions, and this has only gotten worse with Wayland. Even as someone who has been using Arch for years now, I still struggle with getting Plasma to not shit itself every once in a while.
Cinnamon on the other hand does have a lot less features out of the box, but the few things it does, it does them well, and every setting is where a sane person would search for them.
I would not recommend Plasma to a Linux beginner at all. It’s the kind of unpolished mess that would make anyone who doesn’t care enough about computers to just give up and go back to Windows.
I am running Plasma 6.2.1 as we speak. Admittedly, yes, using Arch has certainly made it less stable. But more often than not, when I search the web for some strange behavior/bug/limitation in my desktop, I often find dozens of threads with lots of people reporting the same misbehavior or limitation from all over the distro space, and I have come to the conclussion that it’s not entirely Arch’s fault at that point.
Have you done literally any customization to panels? I swear that shit keeps crashing whenever I do so much as unpinning a simple app launcher plasmoid, and even if it didn’t crash, it still takes patience to navigate through all the menus. They completely overhauled the way panel settings look and behave, and I still find the experience annoying as hell. In contrast, customizing panels is pretty straightforward in Cinnamon, and works as expected. It merely doesn’t look as good.
I don’t hate Plasma, or else I would have switched to another DE by now, but this is mostly because I have learned to tame it, and that took a lot of effort that no beginner should have to go through. Cinnamon is like, the polar opposite of that, which is why I’m okay with it being religiously recommended to beginners.
KDE’s priorities are just kinda weird. I have the similar issues with Krita, an otherwise excellent drawing program.