When a screen is locked, we don't need to move the mouse, or press the spacebar, or nudge the thumbpad, or anything like that to unlock it. All we need to do is start typing our password and that takes care of everything.
Makes me think of all the time and trouble I could have saved all these years if I'd only discovered that sooner.
By the way, I discovered this on Budgie, with a plain black screen as a lock screen. I point that out in case somebody finds that it doesn't work on some other DE, or in combination with some other lock screen.