I once needed an app which was only available in the US App Store, so I installed it using my US Apple ID. Now, months later when I want to update apps, many of them require the US Apple ID but even though that was NOT the Apple ID they were "purchased" with (most of these apps are free).
I am 100% certain these apps were not downloaded with the US account.
My question: How can iOS switch the ID used to purchase apps even though they were not downloaded with that particular account?
It's important to mention that as soon as I installed the US app I switched back to my normal Apple ID (and therefore the other store not being the US one).
This is not the first time I have seen this. I remember seeing this a few years back on an another iPhone.