pyqt deployed on android still in memory after exit using CloseEvent

[arjan at annetteenarjan.nl]

I have a pyqt5 application. On app exit the closeEvent method is used so
the user can choose to save data (or not). The code is similar to the
snipped in this tutorial
(https://learndataanalysis.org/example-of-how-to-use-the-qwidget-close-event-pyqt5-tutorial/)
I ported the app to Android using pyqtdeploy 3.1.1. and it is working fine.
However, after the application exists, it is still in the memory of the
Android device. Swiping the app-window upward (even several times) does
also not remove the app from the memory.
If the closeEvent override is not used, the app seems to close cleanly.

Is there a solution to this behavior?