QOpenGLFunctions_4_5_Core leads to memory leak

It seems that  "QOpenGLFunctions_4_5_Core::initializeOpenGLFunctions" leaves several leaking blocks. This can be reproduced with Qt's HelloGL2 example with little modification. 

- class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions
+ class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions_4_5_Core 

and adding #include <QOpenGLFunctions_4_5_Core>

Steps to reproduce:

Run attached example on RHEL8

1. Click on "Unlock"
2. Select "Add new" from menu "Window"
3. Select "Quit" from menu "Window".

Observe several leaking blocks related to for every repetition of steps 1 and 2, which means, the leak increases if glwidgets are created and destroyed during the lifetime of an application.

Also attaching above modified example and valgrind report.