Upon restart, looks like this: https://pasteboard.co/tc6bgGaOHnal.png
After doing : right-click, Configure..., check "Show Title", Apply, uncheck "Show Title", Apply again, shows normally, like this: https://pasteboard.co/W0g3ALxAvFMe.png

==== configuration ====
[Containments][27][Applets][56]
immutability=1
plugin=org.kde.plasma.systemmonitor.cpu

[Containments][27][Applets][56][Configuration]
CurrentPreset=org.kde.plasma.systemmonitor
PreloadWeight=42

[Containments][26][Applets][56][Configuration][Appearance]
chartFace=org.kde.ksysguard.piechart
showTitle=false
title=Total CPU Use

[Containments][27][Applets][56][Configuration][ConfigDialog]
DialogHeight=540
DialogWidth=720

[Containments][27][Applets][56][Configuration][SensorColors]
cpu/all/usage=61,174,233

[Containments][27][Applets][56][Configuration][Sensors]
highPrioritySensorIds=["cpu/all/usage"]
lowPrioritySensorIds=[]
totalSensors=["cpu/all/usage","cpu/all/averageFrequency"]

[Containments][27][Applets][56][Configuration][org.kde.ksysguard.piechart][General]
showLegend=false
==== ====