I'm pretty sure the intended use is to use it like a laser pointer when doing a presentation, but if you can't see the presentation then it defeats the purpose.
Yes, that certainly would spoil your presentation!
Is it blurring your whole screen? I haven’t used it in maybe a year, but I remember it just blurring a small piece (maybe a couple inches) just to help keep track of the pointer.
What makes you believe this? Is there any info from other users, or relevant developer or user manual?
If you know what you want to do, you can use a udev rule (for HW triggering), and/or a script, or other combination. But I don’t know any normal way of doing it.
I don't think there's any way of doing it through the desktop environment, but I do think it can be fixed with some tinkering in the terminal
-whatever app controls the desktop effects, is blurring what is behind applications with transparency.
-the pointer must be running as window that is fully transparent apart from the pointer itself. and since it becomes the active window, the presentation is considered to be behind the active window so it gets blurred.
-if you can add an exception in the configuration file for the blur effect to ignore kde-connect, you could keep the blurring effect and still use the pointer feature
I don't know if this is possible, nor am i experienced enough to know how to do it, but ill play around with it this weekend