I may have encountered the same or a very similar problem. I have kmail crashing several times a day when moving mails between folders (via context menu in mail list) on a Fedora Linux KDE spin system that is not even one week old.
I ran the kmail binary via gdb with debuginfod enabled to get the following output. The first few lines may be older and not directly related to the crash:

qt.qpa.wayland: setGrabPopup called with a parent, QtWaylandClient::QWaylandXdgSurface(0x5555570d4e70) which does not match the current topmost grabbing popup, QtWaylandClient::QWaylandXdgSurface(0x55555737bdf0) According to the xdg-shell protocol, this is not allowed. The wayland QPA plugin is currently handling it by setting the parent to the topmost grabbing popup. Note, however, that this may cause positioning errors and popups closing unxpectedly because xdg-shell mandate that child popups close before parents
qt.qpa.wayland: setGrabPopup called with a parent, QtWaylandClient::QWaylandXdgSurface(0x5555570d4e70) which does not match the current topmost grabbing popup, QtWaylandClient::QWaylandXdgSurface(0x555556bbb930) According to the xdg-shell protocol, this is not allowed. The wayland QPA plugin is currently handling it by setting the parent to the topmost grabbing popup. Note, however, that this may cause positioning errors and popups closing unxpectedly because xdg-shell mandate that child popups close before parents
[Thread 0x7ffee9bff6c0 (LWP 32407) exited]
[Thread 0x7fff6ffff6c0 (LWP 32406) exited]
[Thread 0x7fff75ffb6c0 (LWP 29371) exited]
Downloading separate debug info for /usr/lib64/qt5/plugins/kf5/FrameworkIntegrationPlugin.so
Downloading separate debug info for /usr/lib64/libcanberra-0.30/libcanberra-pulse.so
[New Thread 0x7fff75ffb6c0 (LWP 32420)]
[Detaching after fork from child process 32421]
[Detaching after fork from child process 32423]
[New Thread 0x7fff6ffff6c0 (LWP 32426)]
[Detaching after fork from child process 32427]
[Thread 0x7fff6ffff6c0 (LWP 32426) exited]
org.kde.pim.messagelist: Requested invariant for storage row index  3809  not found in history
org.kde.pim.messagelist: Requested invariant for storage row index  3809  not found in history
org.kde.pim.messagelist: Requested invariant for storage row index  3809  not found in history
org.kde.pim.messagelist: Requested invariant for storage row index  3809  not found in history
org.kde.pim.messagelist: Requested invariant for storage row index  3809  not found in history
[New Thread 0x7fff6ffff6c0 (LWP 32471)]
[New Thread 0x7ffee9bff6c0 (LWP 32472)]
[New Thread 0x7ffeea7ff6c0 (LWP 32473)]
qt.qpa.wayland: setGrabPopup called with a parent, QtWaylandClient::QWaylandXdgSurface(0x5555570d4e70) which does not match the current topmost grabbing popup, QtWaylandClient::QWaylandXdgSurface(0x7fff6003f460) According to the xdg-shell protocol, this is not allowed. The wayland QPA plugin is currently handling it by setting the parent to the topmost grabbing popup. Note, however, that this may cause positioning errors and popups closing unxpectedly because xdg-shell mandate that child popups close before parents
qt.qpa.wayland: setGrabPopup called with a parent, QtWaylandClient::QWaylandXdgSurface(0x5555570d4e70) which does not match the current topmost grabbing popup, QtWaylandClient::QWaylandXdgSurface(0x55555729bca0) According to the xdg-shell protocol, this is not allowed. The wayland QPA plugin is currently handling it by setting the parent to the topmost grabbing popup. Note, however, that this may cause positioning errors and popups closing unxpectedly because xdg-shell mandate that child popups close before parents
malloc(): unaligned fastbin chunk detected

Thread 1 "kmail" received signal SIGABRT, Aborted.
__pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
Downloading source file /usr/src/debug/glibc-2.36-9.fc37.x86_64/nptl/pthread_kill.c
44            return INTERNAL_SYSCALL_ERROR_P (ret) ? INTERNAL_SYSCALL_ERRNO (ret) : 0;
(gdb) bt
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1  0x00007fffee2afec3 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#2  0x00007fffee25fa76 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3  0x00007fffee2497fc in __GI_abort () at abort.c:79
#4  0x00007fffee2a408e in __libc_message (action=action@entry=do_abort, fmt=fmt@entry=0x7fffee3bd465 "%s\n") at ../sysdeps/posix/libc_fatal.c:155
#5  0x00007fffee2b9b9c in malloc_printerr (str=str@entry=0x7fffee3c0400 "malloc(): unaligned fastbin chunk detected") at malloc.c:5660
#6  0x00007fffee2bd00c in _int_malloc (av=av@entry=0x7fffee3f6c80 <main_arena>, bytes=bytes@entry=24) at malloc.c:3849
#7  0x00007fffee2bdded in __GI___libc_malloc (bytes=24) at malloc.c:3323
#8  0x00007fffee4aec0c in operator new (sz=sz@entry=24) at ../../../../libstdc++-v3/libsupc++/new_op.cc:50
#9  0x00007fffecd84076 in QTimer::singleShot<int, Akonadi::JobPrivate::startQueued()::<lambda()> > (interval=0, timerType=Qt::PreciseTimer, slot=..., context=0x555556bb2e40) at /usr/include/qt5/QtCore/qtimer.h:151
#10 QTimer::singleShot<int, Akonadi::JobPrivate::startQueued()::<lambda()> > (slot=..., context=0x555556bb2e40, interval=0) at /usr/include/qt5/QtCore/qtimer.h:146
#11 Akonadi::JobPrivate::startQueued (this=0x55555bea6e30) at /usr/src/debug/kf5-akonadi-server-22.12.3-1.fc37.x86_64/src/core/jobs/job.cpp:190
#12 0x00007fffeeac8134 in QObject::event (this=0x555555bbaa60, e=0x55555be7ce60) at kernel/qobject.cpp:1347
#13 0x00007fffef7aed62 in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x555555bbaa60, e=0x55555be7ce60) at kernel/qapplication.cpp:3640
#14 0x00007fffeea9d4e8 in QCoreApplication::notifyInternal2 (receiver=0x555555bbaa60, event=0x55555be7ce60) at kernel/qcoreapplication.cpp:1064
#15 0x00007fffeea9d6d2 in QCoreApplication::sendEvent (receiver=<optimized out>, event=<optimized out>) at kernel/qcoreapplication.cpp:1462
#16 0x00007fffeeaa0854 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x55555557d3b0) at kernel/qcoreapplication.cpp:1821
#17 0x00007fffeeaa0aec in QCoreApplication::sendPostedEvents (receiver=<optimized out>, event_type=<optimized out>) at kernel/qcoreapplication.cpp:1680
#18 0x00007fffeeaeeb07 in postEventSourceDispatch (s=0x5555555a4e00) at kernel/qeventdispatcher_glib.cpp:277
#19 0x00007fffe844bc7f in g_main_dispatch (context=0x7fffd4005010) at ../glib/gmain.c:3454
#20 g_main_context_dispatch (context=0x7fffd4005010) at ../glib/gmain.c:4172
#21 0x00007fffe84a2118 in g_main_context_iterate.constprop.0 (context=0x7fffd4005010, block=1, dispatch=1, self=<optimized out>) at ../glib/gmain.c:4248
#22 0x00007fffe8448f00 in g_main_context_iteration (context=0x7fffd4005010, may_block=1) at ../glib/gmain.c:4313
#23 0x00007fffeeaee5fa in QEventDispatcherGlib::processEvents (this=0x5555555a9ec0, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#24 0x00007fffeea9bf3a in QEventLoop::exec (this=this@entry=0x7fffffffd3e0, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#25 0x00007fffeeaa4002 in QCoreApplication::exec () at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#26 0x00007fffeef5fad0 in QGuiApplication::exec () at kernel/qguiapplication.cpp:1863
#27 0x00007fffef7aecd9 in QApplication::exec () at kernel/qapplication.cpp:2832
#28 0x0000555555558dbf in main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/kmail-22.12.3-1.fc37.x86_64/src/main.cpp:185

Created attachment 163869 [details]
kcrash log file