Whilst taking a look at the apps that have permissions to view my location in iOS 13.2.3 from Settings/Privacy/Location Services, I've noticed that the stock Maps app is only listed as having access to my location "Whilst Using". Interestingly, however, whilst a navigation is in progress I can appear to be able to navigate away from the app to my Home Screen and still receive navigational instructions. Is this due to this app using a different location model to apps downloaded from the App Store? My assumption would be that as soon as I navigate away from Maps, location access should then be withdrawn.
Taken from this Apple Developer article:
"In general, iOS apps are considered in use when they're in the foreground or running in the background with the background location usage indicator enabled."
Since the navigation is still in progress, the App is running in the background and therefore considered as "in use".