To elaborate on this, we (we as in other developers in KDE, not me personally) have created KDE Neon (https://neon.kde.org/) which is Ubuntu LTS + the latest KDE software. It's great for using the up-to-date KDE Plasma & application versions while having a stable base in Ubuntu LTS.
I've personally used it for nearly 3 years now, and never had any problems with KDE Neon. It probably isn't a good option if you'd like to have the newest versions everywhere, since the base system is only thoroughly upgraded on every Ubuntu LTS release.
If you have any questions regarding KDE software or KDE Neon, I'd be happy to answer them on #kde:kde.org (Matrix) which is also bridged to #kde on freenode.
I've been a happy KDE Neon user on my secondary desktop, an Intel NUC, for about 3-4 years now. I use it multiple hours each day and it's been a very pleasant experience, as in it does its thing and doesn't get in my way.
Was seriously considering using it for my primary desktop, but that'll have to wait until there's a viable RDP alternative.
I've personally used it for nearly 3 years now, and never had any problems with KDE Neon. It probably isn't a good option if you'd like to have the newest versions everywhere, since the base system is only thoroughly upgraded on every Ubuntu LTS release.
If you have any questions regarding KDE software or KDE Neon, I'd be happy to answer them on #kde:kde.org (Matrix) which is also bridged to #kde on freenode.