Since updating Qt to 5.15.2 yesterday I got kwin crashing twice when I was typing in brave browser. It obviously doesn't crash reproducably. The backtrace was the same both times: === Application: KWin (kwin_x11), signal: Segmentation fault [KCrash Handler] #4 0x00007f9b4287a150 in () at /usr/lib/libxkbcommon-x11.so.0 #5 0x00007f9b4287b2b4 in xkb_x11_keymap_new_from_device () at /usr/lib/libxkbcommon-x11.so.0 #6 0x00007f9b3b25cb89 in () at /usr/lib/libQt5XcbQpa.so.5 #7 0x00007f9b3b2563cf in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/libQt5XcbQpa.so.5 #8 0x00007f9b3b256c69 in QXcbConnection::processXcbEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5XcbQpa.so.5 #9 0x00007f9b3b27a54e in () at /usr/lib/libQt5XcbQpa.so.5 #10 0x00007f9b412df3fc in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5 #11 0x00007f9b412e7894 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5 #12 0x0000559c6251f412 in () #13 0x00007f9b40c81152 in __libc_start_main () at /usr/lib/libc.so.6 #14 0x0000559c6251f94e in _start () [Inferior 1 (process 5995) detached] === Unfortunately archlinux has no (easy) way to install debug libs, so this probably isn't useful.
This bug was reported against an outdated version of KWin. We have made many changes since the. If the issue persists in newer versions can you reopen the bug report updating the version number.