It would be nice if Plasma would be able to do a sort of "smart switching" between mouse and touchpad for laptops. What this means, is if a mouse is connected, then the touchpad automatically gets disabled without user interaction. When the user later unplugs the mouse then the touchpad enables itself without user interaction.

STEPS TO REPRODUCE
1. Using a laptop, plug in a mouse
2. Start typing and accidentally slightly touch the touchpad
3. Your cursor goes all over and you might get angry

OBSERVED RESULT
Due to the touchpad not being disabled upon the mouse being connected, and the user did not go out of their way to disable the touchpad for any many of reasons. When they started typing and their finger or palm slightly touched the touchpad the cursor moved all over and they got frustrated.

EXPECTED RESULT
When plugging in the mouse, the touchpad automatically disabled itself to avoid any frustration or extra steps needed by the user.

SOFTWARE/OS VERSIONS
OS: Arch Linux x86_64
Kernel: 5.14.15-arch1-1
(available in About System)
KDE Plasma Version: 5.23.2
KDE Frameworks Version: 5.87.0
Qt Version: 5.15.2
Graphics Platform: X11

Dolphin flatpak version: 21.08.2
Flatpak version: flatpak 1.12.2-1
Flatseal version: 1.7.4