> Can the mouse scroll speed be configured in KDE, nowadays?
> (hint: the reasonable expectation, IMHO, would be to "open System Settings, go to Mouse Settings, and change a slider")
Yes. This is more or less what KDE does everywhere the upstream software stack supports it, and probably also what it already did the last time you tried it. This comes down to your distro's display server configuration.
On Xorg, mouse scroll speed is up to your X11 input driver, not your desktop environment. If the X11 input driver you're using for your mouse supports setting the scroll speed, that setting shows up in System Settings in your Plasma session. Libinput doesn't support this feature, so if you're on Xorg and you want it, don't use libinput as your mouse driver.
Under Wayland (which also uses libinput), the compositor mediates all input and so the KDE folks have worked around the issue and implemented the feature themselves.
> (hint: the reasonable expectation, IMHO, would be to "open System Settings, go to Mouse Settings, and change a slider")
Yes. This is more or less what KDE does everywhere the upstream software stack supports it, and probably also what it already did the last time you tried it. This comes down to your distro's display server configuration.
On Xorg, mouse scroll speed is up to your X11 input driver, not your desktop environment. If the X11 input driver you're using for your mouse supports setting the scroll speed, that setting shows up in System Settings in your Plasma session. Libinput doesn't support this feature, so if you're on Xorg and you want it, don't use libinput as your mouse driver.
Under Wayland (which also uses libinput), the compositor mediates all input and so the KDE folks have worked around the issue and implemented the feature themselves.
See the upstream issue in libinput here: https://gitlab.freedesktop.org/libinput/libinput/-/issues/74...