Created attachment 134345 [details]
Screenshot of energy system tray icon with battery connected message.

SUMMARY
Since one of the recent updates, KDE power management regularly fails to recognise when I disconnect my notebook charger. It will show that a charger is connected but that the battery is still being discharged. It will then run down the battery to 0% without further warning about battery level. When the power level reaches 0%, the system crashes.

This is on a Thinkpad X1 Yoga 3rd. I use openSUSE TW with TLP 1.3.1 for power management. tlp-stat reports the system as running on battery. 

STEPS TO REPRODUCE
1. Run notebook on AC
2. Disconnect power adapter.

Note that this is not perfectly reproducible, but it occurs like this for me at least 2/3 of the time.

OBSERVED RESULT
KDE system tray icon reports "battery at X%, connected but still being discharged", shows green charger icon superimposed over battery. The system will not honour battery power settings and will run down the battery without any warning until it is totally empty, at which point the computer switches off without going through shutdown. 

EXPECTED RESULT
KDE system tray icon should show charger as disconnected.
Power settings should be honoured.
When reaching low charge levels, I should receive a warning.

SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20201224
KDE Plasma Version: 5.20.4
KDE Frameworks Version: 5.77.0
Qt Version: 5.15.2
Kernel Version: 5.9.14-1-default
OS Type: 64-bit
System: Lenovo Thinkpad X1 Yoga 3rd gen
Processors: 8 × Intel® Core™ i7-8550U CPU @ 1.80GHz
Memory: 15.5 GiB of RAM

ADDITIONAL INFORMATION
Power management with TLP 1.3.1 (OpenSUSE rpm package).