Maybe give Aurora a chance.
It's basically a slightly altered variant of Kinoite with many QoL-changes and additions.

And there's also Bazzite, which is the same, but for gaming purposes.

They belong to the uBlue-family, which is one of the coolest things ever in the Linux world for me

It is certainly helpful in preventing issues caused by packages updating, as the whole base image should remain consistent (and you could always just roll back to the previous update from grub if necessary and revert a commit that broke your system). Since you were using Arch, I made a baseless assumption that you would want the ability to modify the root filesystem for configuration, but it was a baseless assumption, so if that is not the case, then atomic distros are great for users that don't want to tweak tiny things in root directories like /usr. Granted, you can still overlay stuff if you wanted, so it's not as if you couldn't tweak stuff in immutable directories, it just requires a bit more work to do on atomic distros.

If what you're looking for is a standard desktop KDE experience with a distro that is more resistant to breakage, I'd highly recommend Kinoite. It requires a bit of learning, but not a whole lot. For instance, the typical order of priority for installing packages is flatpak (mostly GUI stuff) > toolbox (terminal-based packages like neovim that aren't already installed) > overlay with rpm-ostree (basically the equivalent of installing through your package manager). The fewer overlays you have, the better your protection from spontaneous breakage is. Of course, there are packages you will have to overlay depending on the situation (like the proprietary Nvidia drivers), but almost everything I need was available as either a flatpak or was practical to install in toolbox (basically a containerized mutable root that lets you install stuff with dnf instead of rpm-ostree). You can add aliases to your .bashrc so you don't have to type "toolbox run " every time, as well. Just be aware that packages installed in toolbox live in a container, and they aren't intended to be able to break out of the container (so if you open a terminal in neovim, which is installed in a toolbox container, it will open a shell inside the container, not on your host). Containers can access your home directory and a variety of different directories in your system, so this often isn't an issue, it's just something to keep in mind (for instance, you can't enable systemd services on your host from inside a terminal).