"Unlock functionality" prompt on iOS

[brothom 224]

I tried granting one of my users access to my Emby server and while the browser via app.emby.media works fine, the iOS app doesn't. 

When the user tries to play any sort of media, they're immediately prompted to:
* purchase premium for €7,99
* "unlock" for € 5,99 (whatever that means)
* or to restore purchase.

None of my other users receive this message. This user is on an iPhone 17 pro and I have a sneaking suspicion it has something to do with Apple stuff, hence why I'm posting here.

Anyone have any clue?