Qt for Python (PySide/Shiboken)

Hello. Why, after converting ui to pyside6, the program window became larger and the quality deteriorated. How can this be fixed?

QML? Or?

Can you maybe post a screenshot of the effect?

To me it looks like a different theme.

And what are the possibilities to fix it?

Your question was about the difference between pyside2 and 6 :) the screenshot shows qtcreator

Noo, between pyside 6 and qt designer.