what or how KDE health checker works and monitor battery? sees like my KDE battery health is just on each boot going down on KDE now it shows already battery health 54% 2 days ago KDE shows 79% this must be a KDE bug
All DE query the kernel via the /sys file system
Look in the folder /sys/class/power_supply/BAT0 and you will find the details. capacity is the percent full.
If it is a bug its in the kernel/BIOS firmware not KDE.