SUMMARY
I have Celluloid player from flathub installed on my system,
Plasma shows many notifications about xdg-desktop-portal-kde crash
when I open a video with it via Dolphin.

SOFTWARE/OS VERSIONS
Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.22.80
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.3
Graphics Platform: X11


Application: xdg-desktop-portal-kde (xdg-desktop-portal-kde), signal: Segmentation fault
Content of s_kcrashErrorMessage: std::unique_ptr<char []> = {get() = 0x0}
[New LWP 18252]
[New LWP 18256]
[New LWP 18257]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/usr/lib/x86_64-linux-gnu/libexec/xdg-desktop-portal-kde'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  __GI_raise (sig=sig@entry=11) at ../sysdeps/unix/sysv/linux/raise.c:50
[Current thread is 1 (Thread 0x7f74ca7e11c0 (LWP 18252))]
__preamble__

[Current thread is 1 (Thread 0x7f74ca7e11c0 (LWP 18252))]

Thread 3 (Thread 0x7f74c9145700 (LWP 18257)):
#0  0x00007f74ce3afaff in __GI___poll (fds=0x7f74bc004e60, nfds=2, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f74ccd0e36e in g_main_context_poll (priority=<optimized out>, n_fds=2, fds=0x7f74bc004e60, timeout=<optimized out>, context=0x7f74bc000c20) at ../../../glib/gmain.c:4346
#2  g_main_context_iterate (context=context@entry=0x7f74bc000c20, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../glib/gmain.c:4042
#3  0x00007f74ccd0e4a3 in g_main_context_iteration (context=0x7f74bc000c20, may_block=may_block@entry=1) at ../../../glib/gmain.c:4108
#4  0x00007f74ce97cfb2 in QEventDispatcherGlib::processEvents (this=0x7f74bc000b60, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#5  0x00007f74ce92125b in QEventLoop::exec (this=this@entry=0x7f74c9144bb0, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:141
#6  0x00007f74ce73ac22 in QThread::exec (this=this@entry=0x7f74cec62d80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#7  0x00007f74cebdef4b in QDBusConnectionManager::run (this=0x7f74cec62d80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at qdbusconnection.cpp:179
#8  0x00007f74ce73bdbc in QThreadPrivate::start (arg=0x7f74cec62d80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread_unix.cpp:329
#9  0x00007f74ce193609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#10 0x00007f74ce3bc293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7f74c9c70700 (LWP 18256)):
#0  0x00007f74ce3afaff in __GI___poll (fds=fds@entry=0x7f74c9c6fae8, nfds=nfds@entry=1, timeout=timeout@entry=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f74cd8dec1a in poll (__timeout=-1, __nfds=1, __fds=0x7f74c9c6fae8) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46
#2  _xcb_conn_wait (c=c@entry=0x563b6f74d000, cond=cond@entry=0x563b6f74d040, vector=vector@entry=0x0, count=count@entry=0x0) at ../../src/xcb_conn.c:480
#3  0x00007f74cd8e090a in xcb_wait_for_event (c=c@entry=0x563b6f74d000) at ../../src/xcb_in.c:697
#4  0x00007f74ca3a6e58 in QXcbEventQueue::run (this=0x563b6f73e0d0) at qxcbeventqueue.cpp:228
#5  0x00007f74ce73bdbc in QThreadPrivate::start (arg=0x563b6f73e0d0) at thread/qthread_unix.cpp:329
#6  0x00007f74ce193609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#7  0x00007f74ce3bc293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7f74ca7e11c0 (LWP 18252)):
[KCrash Handler]
#3  KWayland::Client::ConnectionThread::display (this=this@entry=0x0) at ./src/client/connection_thread.cpp:239
#4  0x00007f74d0da56f0 in KWayland::Client::EventQueue::setup (this=0x563b6f815de0, connection=0x0) at ./src/client/event_queue.cpp:62
#5  0x0000563b6d8c1ed7 in WaylandIntegration::WaylandIntegrationPrivate::setupRegistry (this=0x563b6d9134c0 <(anonymous namespace)::Q_QGS_globalWaylandIntegration::innerFunction()::holder>) at ./src/waylandintegration.cpp:455
#6  0x0000563b6d8c2214 in WaylandIntegration::WaylandIntegrationPrivate::initWayland (this=<optimized out>) at ./src/waylandintegration.cpp:421
#7  0x0000563b6d88661d in DesktopPortal::DesktopPortal (this=0x563b6f81dad0, parent=<optimized out>) at ./src/desktopportal.cpp:33
#8  0x0000563b6d8699e7 in main (argc=<optimized out>, argv=<optimized out>) at ./src/xdg-desktop-portal-kde.cpp:28