Hi,

exec_ function is deprecated in PySide6, so the common PyQt5/PySide2 code gets deprecated warning when QT_API=pyside6.

DeprecationWarning: 'exec_' will be removed in the future. Use 'exec' instead.
  sys.exit(app.exec_())

On the other hand, PyQt6 removes exec_ but QtPy provides exec_ for the compatibility. (#259)
As a result, DeprecationWarning of exec_ occurs only when QT_API=pyside6.
Which should this DeprecationWarning be addressed by QtPy or the user application?
Note that print_ function of PySide6 may have the same problem.