[Approved] Plasma 6 proposal: Disable scroll on desktop to switch virtual desktops by default
In general it's non-optimal for scrolling to trigger hidden behavior, unless that behavior is benign, does not change the entire screen contents, and seems connected to the thing you scrolled on. Scrolling over the volume icon to change the volume satisfies these criteria; scrolling on the desktop to change the virtual desktop does not. The user can easily scroll on the desktop by accident and have the entire screen contents changed without knowing how to get back. And if the virtual desktop they switched to has a maximized window on it, they won't be able to see the desktop to scroll to get back.
This should be considered an expert feature, and hence disabled by default.