QCoreApplication does not release memory after QThread::run()

I am actually working on a project that makes video file decoding in a separate threads and came along with a memory leak. Project combines Qt and Opencv facilities. And first I have thought that this is Opencv's issue, but after switch from QThread to std::thread the leak is disappeared. All details and code to reproduce can be found in this thread: https://github.com/opencv/opencv/issues/11939