SUMMARY
When moving a cursor between displays, they will get stuck briefly. If you slowly move a cursor it will stick at very close to the screen edge and there will be resistance when trying to move it beyond. This makes it difficult for a cursor to glide slowly across many displays at once, such as from one display across to a fourth display horizontally (although this effect also happens for displays that are stacked vertically, and for arrangements with displays arranged horizontally and vertically).

If the cursor is moving very fast, the resistence is less noticeable, but can still be felt.

This felt like a Desktop Effect or some kind of intentional behaviour, because it can make splitting windows slightly easier, but it impacts the default mouse behaviour. If the intent was to make tiling easier then this should ideally only apply if a window is being tiled, not for regular desktop usage. Even so, I would also say it should be optional behaviour, on by default, sure, but it should also be togglable as it is a significant change in behaviour from previous Plasma versions and other DEs/operating systems (unless something has changed significantly).

I could not find any setting to turn this off, so I am filing it as an issue in case this is some kind of optional functionality. I don't know if this is intended to be a default, as this is not behaviour I have seen before on any Desktop Environment / Wayland Compositor (GNOME 3 way back, Xfce, Hyprland, Sway) or operating system with multiple monitors (Windows 10 a long time ago, macOS for work).

I could reproduce this on my desktop, and on a laptop running Plasma 6.1.0 with an external display connected. It did not happen on any previous Plasma version.

If this is intended to be the always-on default behaviour with no way to disable it, please consider making this optional. For cases where you might need to slowly move your mouse from the top right corner of one display to the top right of the adjacent display, this becomes a chore.

STEPS TO REPRODUCE
1. Have multiple  displays arranged next to each other.
2. Move the mouse across displays.
3. The mouse will "stick" to the edge of the display and take resistence to move.

OBSERVED RESULT
Cursor cannot slowly move between screens and gets "stuck" until "pushed" harder across the display.

EXPECTED RESULT
Cursor should not get stuck when crossing a screen border, or should be togglable.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.9.5 Linux Zen
KDE Plasma Version: 6.1.0
KDE Frameworks Version: 6.3.0
Qt Version: 6.7.1

ADDITIONAL INFORMATION
Did not test X11 session.