SUMMARY
Discover crashes on start, while preparing the list of updates. It has started happening since Plasma 5.23.0.

STEPS TO REPRODUCE
1. just open the program.
2. 
3. 

OBSERVED RESULT
Application: Discover (plasma-discover), signal: Segmentation fault

[KCrash Handler]
#4  0x00007f35006d6d58 in FlatpakBackend::findSource(_FlatpakInstallation*, QString const&) const () at /usr/lib64/qt5/plugins/discover/flatpak-backend.so
#5  0x00007f35006dc9b8 in FlatpakBackend::getAppForInstalledRef(_FlatpakInstallation*, _FlatpakInstalledRef*) const () at /usr/lib64/qt5/plugins/discover/flatpak-backend.so
#6  0x00007f35006dff66 in QtPrivate::QFunctorSlotObject<FlatpakBackend::search(AbstractResourcesBackend::Filters const&)::{lambda()#3}, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) () at /usr/lib64/qt5/plugins/discover/flatpak-backend.so
#7  0x00007f35106fee9e in QObject::event(QEvent*) () at /usr/lib64/libQt5Core.so.5
#8  0x00007f3511b26a8f in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib64/libQt5Widgets.so.5
#9  0x00007f35106d44ea in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib64/libQt5Core.so.5
#10 0x00007f35106d7287 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib64/libQt5Core.so.5
#11 0x00007f3510728893 in  () at /usr/lib64/libQt5Core.so.5
#12 0x00007f350d4eb5db in g_main_context_dispatch () at /usr/lib64/libglib-2.0.so.0
#13 0x00007f350d4eb848 in  () at /usr/lib64/libglib-2.0.so.0
#14 0x00007f350d4eb8ef in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#15 0x00007f3510727f64 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#16 0x00007f35106d306b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#17 0x00007f35106dacbc in QCoreApplication::exec() () at /usr/lib64/libQt5Core.so.5
#18 0x0000000000415f3a in main ()
[Inferior 1 (process 28321) detached]

EXPECTED RESULT
Discover working normally without crash.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.23.3
KDE Frameworks Version: 5.87
Qt Version: 5.15.3

ADDITIONAL INFORMATION
Could be related to AppStream-qt >=0.14.4 ? I've tried 0.14.6 but doesn't change.