So like I’ve tried kde plasma a bit not much tho I mainly wanna have a dual boot setup where for office and some light games I use windows but sometimes i will use onlyoffice on Linux as well so I really want a distro which Is stable gives me control over stuff like kde like I can do cool stuff and costomization but I want it to be stable not get a lot of updates that can break stuff if the updates don’t break stuff and are frequent I’ll still call it stable I’ll mainly browse in firejail for my work because those unmaintained govt sites have game a gazillion viruses at this point so in a nutshell i want a stable os in which I can do some cool customization and I have control over it and maybe play some games which support linux and have it as a dual boot and also primarily use it for business purposes
Fedora is good. I personally run Arch—very vanilla, but may require some knowledge to install. Also, I don’t dual boot, which makes things easier. So, yeah: Fedora, or a derivative distro like Bazzite is probably your best bet.
You can try distribution here : Testez les distributions Linux en ligne - DistroSea
There is also : https://distrowatch.com/
For KDE plasma, you have :Kubuntu, Opensuse (leap version is the stable), Manjaro (based on Arch).
the best stable distro for the plasma desktop is kubuntu LTS (currently on plasma 5).
the upgrade to plasma 6 is coming in April, but plasma 5 works VERY well and i plan to keep using it until i see how things settle out for the 26.04 release.
the upgrade path is a GUI button on the so you are in total control of when that takes place.
the other option is to install kubuntu 25.10 now with plasma 6 and upgrade to 26.04 as soon as it’s released.
—
fedora is semi-rolling and changes can come at any time if you accept them.
from what i gather, the best practice for stability on fedora is to install one version older than the current release (so you have 6 months of bug fixes ahead of you), and then watch the updates carefully for anything that might impact your workflow so you can hold those updates back until you are ready… but i’ve never used fedora, so no idea how well that works.
You could try Debian, I’ve used Debian for probably over 2 years in total, I’ve not had many issues with it, The only issues I have are mostly Nvidia driver quirks. The distro is super stable, You can customize a whole lot, I would say it’s pretty easy to install (Despite the aged look of the installer), It’s also extremely well supported by the community, I believe just as much as Ubuntu. So that’s my recommendation! You should do your research though 
strait debian does not put much effort into integrating the plasma desktop with the rest of the OS… it’s just an other package you can throw on the fire
but the plasma desktop is more complicated than that and requires a bit more effort on the part of the distro maintainers to ensure a seamless experience.
if i were to go with strait debian, i would choose the LXQt desktop instead.
Ill Summarize what others have already said and add my own stuff:
Basically, a nice stable distro choice would be either
- Fedora KDE (or Bazzite but i don’t recommend it for you) (my choice)
- Kubuntu LTS
- Opensuse Leap (which i don’t recommend over the next suggestion)
since they are both popular and if anything breaks you have huge communities to help you.
but if you just want things to work and hate when things break, then
- Opensuse Tumbleweed
would be good, since you can backtrack to a version of your desktop that wasn’t broken.
some also recommended
- Debian
but i find Kubuntu to have better support on this forum/
There are other Distros i can recommend but that will only complicate everything. these are the best for what you need!