That’s a thing with Neon. It’s the “testing ground” for new KDE releases so they won’t guarantee stability. It literally is just Ubuntu LTS with a KDE repo thrown on top, and the Neon devs themselves only maintain that repo, with just a short delay after the new Ubuntu LTS release comes out. In Neon, the users are the quality control for KDE releases. I was using it for a little over a year until the rebase to Ubintu 24.04 broke my install. I went to Nobara, a gaming focused distro based on Fedora that uses a custom version of KDE as the default. I just upgraded to the newest version not realizing it wasn’t official yet, and it must have been the smoothest major version upgrade I’ve ever had in a non-rolling distro. It’s maintained by GloriousEggroll, who also builds/maintains the customized GE versions of Proton on Steam. I’m finding it’s not just a good gaming distro but a solid and stable distro overall. GloriousEggroll puts a lot of work into ensuring that on top of the Proton work he does. If you don’t want the gaming performance customizations he makes, try Fedora KDE spin, it’s likely to be pretty similar and I rarely ever hear someone have a problem with Fedora.

On your other question, next time you reinstall you can create a separate Home partition on your drive that should allow you to do what you’re looking for. So you have your boot and swap partitions and the one you install your distro to, and then your home partition, so you just install the new distro over the old distro and it should leave your home partition alone.