I have an Asus Zenbook Duo with two touch screens. When I turn second screen off everything is working perfectly. Otherwise touch from one screen is able to push cursor to the second screen. See gif:
Don't get confused with manjaro linux on the gif. I was trying a few KDE distros and now I know it is how KDE works out of the box on all distros.
I found this question with similar issue: Dual screens where one is touch • KDE Community Forums
Unfortunately I can not map touch input to just one screen because both my screens are touchscreens.
This issue convinced me to use Gnome on my laptop but it just isn't enough for me and I can no longer handle it so I decided to go back to the KDE Plasma which is so much better in customisation. I am also using Garuda KDE for more than year on my desktop computer and I can not imagine better desktop enviroment.
I am looking forward to your replies on how to solve this issue. Thanks.