The way Virtual Desktops work today is to switch to the same VD on all screens simultaneously.
This behavior dramatically disrupts my workflow since I want to switch to another VD only on the screen I’m working in, with the other screen remaining unchanged.
You may be looking for something like this: https://store.kde.org/p/2143363 (note: I haven’t tested this, your mileage may vary).
This kind of feature is not yet built into kwin, so kwin scripts like this one are the way to go for now.