after QCoreApplication::quit and delete still some threads started by Qt are active

I do

    QCoreApplication::quit();
    delete QCoreApplication::instance();

but after that still some Qt related threads are not stopped: dconf worker, gmain, gdbus, QDbusConnection, QQmlThread.

I expect this threads to be stopped too.

I need this because my Qt application is implemented in shared library and after above QCoreApplication::quit/delete QCoreApplication::instance I do unloading of shared library but it crashes. Probably due to above mentioned running threads.