I use the Australian App Store for both my Macbook and iPhone, so would expect the currency to be the same for both, which were both downloaded via the App stores.
Perhaps this is a bug where the Mac app doesn’t show the actual App store price, whereas the iOS app does.
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Another question about pricing. To get the features for iOS, can one purchase the macOS and iOS bundle via the download-from-website-mac-app instead of the download-from-app-store-mac-app? If so, perhaps I will do that as may be cheaper considering how the Australian app store is always more expensive than a simple currency conversion.