I do not know what it means to "use the taskbar with symbols".

NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports

If you can't provide any other information, a video maybe would be a way to explain what you are doing.

Created attachment 144092 [details]
Select Icons-only Task Manager so that only icons instead of bars are shown in the task bar

Developer Information:

Application: Discover (plasma-discover), signal: Aborted

[KCrash Handler]
#4  0x00007fc31ace4d22 in raise () at /usr/lib/libc.so.6
#5  0x00007fc31acce862 in abort () at /usr/lib/libc.so.6
#6  0x00007fc31b11c910 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007fc31b11bd52 in  () at /usr/lib/libQt5Core.so.5
#8  0x00007fc2bf1313fb in FlatpakBackend::findSource(_FlatpakInstallation*, QString const&) const (this=<optimized out>, installation=<optimized out>, origin=<optimized out>) at /home/prroet/Programs/arch-linux-packages/discover/repos/extra-x86_64/src/discover-5.23.3/libdiscover/backends/FlatpakBackend/FlatpakBackend.cpp:427
#9  0x00007fc2bf13fdd0 in FlatpakBackend::getAppForInstalledRef(_FlatpakInstallation*, _FlatpakInstalledRef*) const (this=0x55797ae21a40, installation=0x7fc29c019280, ref=0x55797bdd59d0) at /home/prroet/Programs/arch-linux-packages/discover/repos/extra-x86_64/src/discover-5.23.3/libdiscover/backends/FlatpakBackend/FlatpakBackend.cpp:352
#10 0x00007fc2bf143c00 in operator() (__closure=0x55797bd80ea0) at /home/prroet/Programs/arch-linux-packages/discover/repos/extra-x86_64/src/discover-5.23.3/libdiscover/backends/FlatpakBackend/FlatpakBackend.cpp:1276
#11 QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, FlatpakBackend::search(const AbstractResourcesBackend::Filters&)::<lambda()> >::call (arg=<optimized out>, f=...) at /usr/include/qt/QtCore/qobjectdefs_impl.h:146
#12 QtPrivate::Functor<FlatpakBackend::search(const AbstractResourcesBackend::Filters&)::<lambda()>, 0>::call<QtPrivate::List<>, void> (arg=<optimized out>, f=...) at /usr/include/qt/QtCore/qobjectdefs_impl.h:256
#13 QtPrivate::QFunctorSlotObject<FlatpakBackend::search(const AbstractResourcesBackend::Filters&)::<lambda()>, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=<optimized out>, this_=0x55797bd80e90, r=<optimized out>, a=<optimized out>, ret=<optimized out>) at /usr/include/qt/QtCore/qobjectdefs_impl.h:443
#14 0x00007fc31b37256f in QObject::event(QEvent*) () at /usr/lib/libQt5Core.so.5
#15 0x00007fc31c4c7d62 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#16 0x00007fc31b34541a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#17 0x00007fc31b348519 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/libQt5Core.so.5
#18 0x00007fc31b39ea14 in  () at /usr/lib/libQt5Core.so.5
#19 0x00007fc319af24dc in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0
#20 0x00007fc319b46799 in  () at /usr/lib/libglib-2.0.so.0
#21 0x00007fc319aefbc1 in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#22 0x00007fc31b39e046 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#23 0x00007fc31b343d8c in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#24 0x00007fc31b34c2f4 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#25 0x00005579782dc1c0 in main(int, char**) (argc=<optimized out>, argv=0x7ffd90930960) at /home/prroet/Programs/arch-linux-packages/discover/repos/extra-x86_64/src/discover-5.23.3/discover/main.cpp:213
[Inferior 1 (process 3660) detached]

Ok. I am sorry... it appears to be something different... I thought it was this issue: https://askubuntu.com/questions/1264120/plasma-discover-not-starting-on-kubuntu-20-04. 

But somehow I can no longer reproduce this. I think it has more to do with the flatpak backend I am using. I am sorry for the confusion...

Next time I will be more careful before raising a bug...

No need to apologise, it's good that you reached out. Cheers!

*** This bug has been marked as a duplicate of bug 443745 ***