Bug 494932

SUMMARY
When waking up the screens after inactivity, the brightness are found to be re-synced between the screens (they have the same brightness percentage), erasing the custom percentage one could have set for a specific screen.

STEPS TO REPRODUCE
1. Attached a second screen to your set-up
2. Modify the brightness percentage of one of the screens from the brightness aplet, so that it is different than the one of the other screen.
3. Wait few minutes until the screens go darker due to inactivity.
4. Press a key or move the mouse to wake up to previous brightness

OBSERVED RESULT
The 2 screens go darker after inactivity at the same brightness percentage (step 3).
Then when waking up the screens (step 4), the brightness increases but the new brightness percentages are now  the same between the 2 screens, so we don't recover the original different brightness percentages we set in step 2.

EXPECTED RESULT
The brightness percentages should be reset to the values they had in step 2.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 40
KDE Plasma Version: 6.2.0
KDE Frameworks Version: 6.7.0
Qt Version: 6.7.2

ADDITIONAL INFORMATION
Using different brightness values in different screens is important since the screens do not always have the same brightness range. Best would be to be able to sync the real brightness values (for example in nits) instead of the percentages. It is also sometimes needed than some screens keep a constant brightness (for example in photography or for analysis purposes in some scientific set-ups), therefore, the user should be able to deactivate the brightness sync per screen.