I get that. It’s just to test if KDE + the new kernel is the issue.
Also, neither Hyprland nor Openbox would interfere with your KDE settings, which is why I recommended those two specifically. You could uninstall them immediately after if you want, or keep them to test any future issues like these.
It’s good to identify the exact source(s) of the issue so that you can report it upstream, which is what you should now do, really.
You can do so here: https://community.kde.org/Get_Involved/Issue_Reporting
And here: https://bugs.kde.org/
That’s not how kernels work entirely 
. LTS is always gonna be older because it is generally more stable. Not just older for being older’s sake. And Zen is basically current.
So, please install it and see if it works. You can switch between them as needed.
And see here for a little more info: How to run a stress-free EndeavourOS
Obviously, I’m in opposition to Number 3. I believe he’s somewhat wrong about not having more than one DE/WM, but also somewhat right that they can cause more issues, which is why you should only install ones that don’t conflict with each other.
Don’t know what else you can do except delay the kernel update.