I was using Qt 5.14.2 for developing a Qt3D project where the background color of the scene is black and it was always like this. Seeing that Qt 5.15 came out I updated and now the background color of the scene is white and I didn't touch any of the code. At first all the elements of the scene looked white, but putting these lines in the main.cpp of my code solved that but the background is still white when it should be black, these are the lines:

 QSurfaceFormat glFormat;

glFormat.setVersion(3, 2);                                           

glFormat.setProfile(QSurfaceFormat::CoreProfile);