KSysGuard has a new beta release for testing. KSysGuard was previously released with Plasma but its functionality has mostly been replaced by System Monitor. This separate release is available to give a version of the app which compiles with the new libksysguard and for old time fans. A stable release is expected to be made shortly after Plasma 5.22.
https://download.kde.org/unstable/ksysguard/5.21.90/ksysguard-5.21.90.tar.xz It is signed by release manager Jonathan Riddell with EC94D18F7F05997E <https://sks-keyservers.net/pks/lookup?op=vindex&search=0xEC94D18F7F05997E> https://sks-keyservers.net/pks/lookup?op=vindex&search=0xEC94D18F7F05997E https://download.kde.org/unstable/ksysguard/5.21.90/ksysguard-5.21.90.tar.xz.sig