I would recommend Fedora Kionite, or uBlue KDE/ Bazzite. It's the same as Kionite, but preconfigured with some additional QOL-stuff. Bazzite is the equivalent to Nobara, but also immutable.

I turned into a huge fan for Silverblue (and spins) over the last few weeks.

Especially interesting is the Universal-Blue-project, which offers many "spins" (or to be more precise, new-interpretations and derivates).

You can just install the vanilla Silverblue and then rebase to Kionite, uBlue, Bazzite, and so on. And if you don't like it, just roll back/ re-rebase without any hazzle or risks. Your user data are separated from the system and don't need to get copied from your backup like usually.

What you might like:

• Immutable and hard to break. If something breaks (bad update or user fault), roll back. Works even better than Snapper (Tumbleweed) imo, which is pretty much the best BTRFS-implementation. You don't need to restore it, you just select the image and boot.
• Can be rebased (underlying system swapped out) to anything you want. Switch from KDE to Gnome because it now has a feature you missed? One command, a few minutes waiting time for the download, reboot, and you've got a clean "new" system with all your userdata and stuff unchanged!
• No reboot for updates required, they just install in the background and get applied when you boot up your PC the next time.
• Cutting edge, but stable.
• Doesn't only support Flatpak, but relies on it (at least that's recommended).
• Install any software you want with Distrobox. Arch, Debian, whatever. Comes pre-installed (uBlue at least) and is an integral part of your workflow if you use the terminal.
• Great KDE implementation.