New installation of 22.04 / jammy with Kernel Linux 6.5.0-25-generic x86_64.
Screensaver choices are unticked and power management are set to 'never' but screen goes black in a few minutes until next keystroke to wake screen.
Same settings as previously till 5.15.0-100 after which completely reinstalled.
AFAIK it depends on the DPMS implementation.
For instance: My laptop honours the settings but my desktop doesn't.
There are several ways around it.
You can set it for the current user:
either:
Go to startup preferences (in control panel) and create an entry by clicking the add button. Then fill that entry with the following information:
Name: Stop Screen Blanking
command: xset -dpms s off s noblank s 0 0 s noexpose
comments: This prevents the screen from going blank.
Delay: 0
or
Add to your ~/.xinitrc file any or all of the following lines:
xset s off # don't activate screensaver
xset -dpms # disable DPMS (Energy Star) features.
xset s noblank # don't blank the video device