HI 🖐,
I am on iOS and I have set the "log out time" to 5 minutes and I did not notice the App getting back to Home Screen when I swipe back and I am not required the pin to log in.
You can definitely try to extend the "log out" time to a longer period ... if it is sufficient secure for you. Anyway if the phone is locked no one else should be able to access your bunq App.
Regards
GG