Lubuntu20.04 screen blanking and brightness control

I installed Lubuntu20.04 onto my HP laptop and have noticed that the brightness control simply fades the screen image as the laptop display remains bright. Same goes for screen blanking by the screensaver. In when the blanking takes effect, the image is a blank but the laptop display is still bright. Seems during such operations, the display hardware is not being properly controlled.
Any help and insight greatly appreciated.
I’ve also created a bug incident but no one has acknowledged it. I don’t know if it’s the proper place for this bug. https://bugs.launchpad.net/ubuntu/+source/xscreensaver/+bug/1875787