SUMMARY
Plasma crashed and hung after opening a few windows. Kickoff could still be opened but nothing was interactable. I could not reproduce it again.  

Backtrace:
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0)
    at pthread_kill.c:44
#1  0x00007f42cf88e3d3 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#2  0x00007f42cf83e838 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3  0x00007f42cf828535 in __GI_abort () at abort.c:79
#4  0x00007f42d009fedc in qt_message_fatal (message=<synthetic pointer>..., context=...) at global/qlogging.cpp:1914
#5  QMessageLogger::fatal (this=this@entry=0x7fffff0bfad0, msg=msg@entry=0x7f42d0b9ea23 "%s") at global/qlogging.cpp:893
#6  0x00007f42d073c925 in init_platform (argv=<optimized out>, argc=<optimized out>, platformThemeName=..., 
    platformPluginPath=..., pluginNamesWithArguments=...) at kernel/qguiapplication.cpp:1254
#7  QGuiApplicationPrivate::createPlatformIntegration (this=0x564a0f2c5980) at kernel/qguiapplication.cpp:1481
#8  0x00007f42d073cf99 in QGuiApplicationPrivate::createEventDispatcher (this=<optimized out>)
    at kernel/qguiapplication.cpp:1498
#9  0x00007f42d02935eb in QCoreApplicationPrivate::init (this=this@entry=0x564a0f2c5980) at kernel/qcoreapplication.cpp:835
#10 0x00007f42d073d049 in QGuiApplicationPrivate::init (this=this@entry=0x564a0f2c5980) at kernel/qguiapplication.cpp:1527
#11 0x00007f42d0f75d6e in QApplicationPrivate::init (this=0x564a0f2c5980) at kernel/qapplication.cpp:513
#12 0x00007f42d0f75e94 in QApplication::QApplication (this=<optimized out>, argc=<optimized out>, argv=<optimized out>, 
    _internal=<optimized out>, this=<optimized out>, argc=<optimized out>, argv=<optimized out>, _internal=<optimized out>)
--Type <RET> for more, q to quit, c to continue without paging--
   t kernel/qapplication.cpp:501
#13 0x0000564a0e69d30d in main (argc=<optimized out>, argv=0x7fffff0bffe8)
    at /usr/src/debug/plasma-workspace-5.24.5/shell/main.cpp:82

STEPS TO REPRODUCE
1. Log in to Plasma
2. Open a few windows, i opened Firefox and Konsole

OBSERVED RESULT
Plasmashell  dumped core

EXPECTED RESULT
Plasma doesn't crash

Operating System: Arch Linux
KDE Plasma Version: 5.24.5
KDE Frameworks Version: 5.94.0
Qt Version: 5.15.4
Kernel Version: 5.18.1-arch1-1 (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i3-2310M CPU @ 2.10GHz
Memory: 7,6 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 3000