Another weird thing: on 4.19.0-9, if I leave the screen/display off long enough, like: 1 lock the screen 2 see the display off 3 go out for lunch 4 when return, typing or moving mouse can bring the display back on.
As comparison, if I leave the screen/display off not long enough, like going to take some drink, when I get back, in 4), the display won't be powered back on by typing or moving mouse. I have no idea of what happened...