Linux

KDE Manjaro running on 4 or 5 of my machines, pure stability. It sounds like a hardware issue.

Here are my suggestions to diagnose this.

Option 1. Setup an ssh server, connect from a second computer (or phone via Termux), execute $journalctl -fe, and observe the journal from your second device when the crash occurs. That should help pinpoint the issue.

Option 2. If you don't have a second device, use a non-gui tty, access via Ctrl+Alt+F1. (Usually terminals are available F1 thru F6). Once again execute $journalctl -fe and observe it during the crash.

Tbh option 2 may just be easier especially if you have minimal knowledge of ssh. Good luck, ping me back if you find this helpful and would like more perspective, and apologies if this doesn't help you.

If the entire computer crashes, boot into a terminal and browse journalctl history of previous boots, sorry I don't have these commands off the top of my head but if you need them and ask I will get them for you.

I have non of the issue on my Starlite (Kubuntu)

My PC with the newest Arch Linux seems to have sometimes issues with sleep and freezing on waking up. (Intel CPU + AMD GPU)

Give Cinnamon/Budgie a shot, (I recommend in a vm and see which one you like)both are based on gnome(cinnamon personally its like a combination between gnome 3 ane xfce).
I have the same experience with kde personally(Like it crashes sometimes,looks dated,etc it didnt crash that badly for me), and I decided to desktop hop to Cinnamon.

Yes I have Nvidia

I use it daily and it occasionally may crap out, but it may happen maybe once every few weeks. Can't comment about GPU and the likes as I only have an Intel iGPU which works just fine.

I don't like it, too much desk space wasted on useless crapola. I use Mate, a nice clean desktop with a simple pull-down menu leaving the majority of the space free for work.

Look at the reddit called "unixporn" and search for Xfce. You ll see what's possible with Xfce. For me the KDE crashes are a dealbreaker. My Xfce setup is so simplified, that nothing can be ugly. I use Bspwm for the windows and stripped down Xfce panel (dont touch third party status bars, such as polybar, its waste of time if you already have Xfce). No menu such as Whisker menu, but Rofi instead. I got Xfce stability without the old looking.

I've used it on Endeavour for about a year and on Tumbleweed for eight years before that with no real problems other than plasma-shell occasionally restarting. I have Nvidia and the open drivers.

Those aren't normal issues.
It sounds more like a driver or hardware issue which may only pop up in KDE (Wayland) and not in your other WMs (X11).
As a first step, try logging into the KDE (X11) Session and see if it still happens.

I use Fedora KDE, and I don't think ive ever seen crashes that bad on my system (AMD CPU and GPU). I used to have a small problem with RADV crashing during video playback, but that solved itself after a few updates.

For what it's worth, I experience none of that. My laptop is absolutely rock solid with KDE, it's like a MacBook you pull it out of your backpack and it's ready to go before I'm even done opening the screen.

My desktop is currently just over 5 days of continuous uptime (no sleep). I've crashed more often because of ZFS than KDE.

Both are ArchLinux. I also have a friend on Bazzite that doesn't have issues with KDE either, and it runs great in my VM.

Those all sound like possible graphics driver issues.

If KDE works for you, do you use a preinstalled distro and which one?

Has largely worked fine for me on Tumbleweed.

There is/was an issue with launching some of the 'K' apps causing the desktop to hard lock. But this happens very rarely.

Haven't experienced problems like what you're describing though.

I’ve been using it on two older systems (4-8 y) one without a ssd or graphics card and it works flawlessly. As others suggested maybe you check your graphics drivers. I used to have problem with kde some time ago but since coming back it’s been nothing but smooth sailing.

Is KDE actually good or it is overrated?

That's like a trick question 😀
If I say it's good, and that contradicts your own experience with it, you can say "see it's overrated, people say it's good, but in fact I know it sucks."

I use it on Arch but I've seen people using it on Fedora and it looked good and stable.

Did you try to look into it, see what's causing the problems?
In my experience having used Linux and KDE Plasma for about a decade now, if you wanna have a good time you're going to have to figure stuff out, check the logs, troubleshoot, look it up online, etc.
If you expect to go through different distros to find one that "just works" you'll be disappointed, and you'll be wasting your time. Issues can be hardware-specific, maybe you just need to pass a parameter to the kernel, or change a config somewhere or something like that...

Do you have an nvidia GPU? It's the most important thing to know.