When a tablet's stylus is active the touch events will be ignored so that you can place your hand on the touch screen and use the stylus without triggering touch events.
When I used X, I used
xinput disable <device> to disable the touch screen which is an unpleasant user experience. With Wayland this option does not work anymore (see #243). This MR provides a smother solution by filtering touch events while a stylus is in use: