Weird behaviour of QPainter::render() in QT 6.0.0

[glafauci]

Good morning to all.
I'm developing a project that needs to create some QR codes. I realized it using a QGraphicsScene, populate it with grahics and text, and then saving any scene in SVG and PDF using a for cycle.

I started using QT6.0.0; I noticed that the graphics elements used to populate the scene were correctly saved. Instead, the text was saved in SVG files, but not saved in PDF files.

After several attempts, I switch the configuration to QT 5.15.2, and all was correctly stored!!

All fine, except that the SVG shows a different text font size for the same scene.

So, there are two suspected bugs:

1. When I save the same scene in SVG and PDF, I obtain a different graphical representation for text;
2. Using QT 6.0.0, saving the scene in SVG is correct; in PDF the system doesn't print text.

I link a project that shows what I say.