SUMMARY
In the original system monitor, selecting a process and pressing shift+delete (instead of just delete) shows a window confirming the killing of the process (not just SIGTERM).

In the new system monitor, the support for sending SIGTERM for delete was recently added but the support for shift+delete for sending SIGKILL wasn't causing a feature regression between the old and new system monitor.

STEPS TO REPRODUCE
1. Go to plasma-systemmonitor
2. Go to processes
3. Select a process
4. Press delete (works) and then ok
5. Press shift+delete (does nothing)

OBSERVED RESULT
Pressing delete and accepting the popup sends SIGTERM
Pressing shift+delete does nothing

EXPECTED RESULT
Pressing shift+delete should show a force kill popup saying that it will "immediately and forcibly kill" the process in bold then send a SIGKILL when accepted


SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.22.2
KDE Frameworks Version: 5.83.0
Qt Version: 5.15.2
Kernel Version: 5.12.12-zen1-1-zen (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-8565U CPU @ 1.80GHz
Memory: 15.4 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics 620

ADDITIONAL INFORMATION
Attached screenshot shows pressing delete and shift+delete in the old system monitor.
Both Delete and Shift+Delete also work for KSysguard