I confirm this bug exists on my laptop, which is an ASUS UX305C. I just upgraded to Buster, and the bug appears. To be specific:
If I lock the screen (by pressing Ctrl-Alt-Del, selecting "Lock Screen", closing the laptop lid, or letting the screensaver time out), then the screen goes black, as expected. If I then move the mouse or hit keys on the keyboard, the screen does not stop being black. However, if I then type Ctrl-Alt-F1, I get a working console login. If I then type Ctrl-Alt-F7, I get a message about the screen being locked, and if I type Ctrl-Alt-F8, I get the unlock screen. If I then leave the laptop for a while on the unlock screen, the screen will go black again, with the same consequences - moving the mouse or hitting keys on the keyboard does not bring the screen up again.
I would very much appreciate any progress being made on this bug, despite there being a workaround.
Matthew
