Using the three finger gesture in a touchscreen to move between a workspace that is focused in the wallpaper to any other virtual desktop will trigger the edit mode very easily (you actually need to be very cautious and fast to not trigger it). It also selects a blue square very easily, which is more like visually annoying than anything else. 

I'm almost sure this behavior is very new from the last few versions of Plasma 6 (maybe the 6.0.5 itself), and I can help with it if it narrows down to a small number of recent commits related to touchscreen.