Once upon a time, Qt was GPL + commercial. A separate project - PyQt - came and was GPL + commercial too.
Later, Qt became GPL + LGPL + commercial. However, PyQt, didn't want to add LGPL and stayed dual licensed. Qt thought "ok then, will have to do it by myself" and created an alternative to PyQt called PySide, which was GPL + LGPL + commercial.
That was in Qt4 time. Then Qt5 came, and PyQt5 appeared, while PySide was still in Qt4 land.
Then PySide2 happened, now known as Qt for Python.
Later, Qt became GPL + LGPL + commercial. However, PyQt, didn't want to add LGPL and stayed dual licensed. Qt thought "ok then, will have to do it by myself" and created an alternative to PyQt called PySide, which was GPL + LGPL + commercial.
That was in Qt4 time. Then Qt5 came, and PyQt5 appeared, while PySide was still in Qt4 land.
Then PySide2 happened, now known as Qt for Python.