"Unable to restore" due to different Apple ID: how to find which apps are causing this?

Hello all,

until a month ago my father used an old iPad Air 2 (his 3rd iPad). Back in the day, I had originally set his first iPad up using my own Apple ID, but ultimately created his own Apple ID to keep things separate. It all worked well and he could install apps without needing my password.

A month ago I gave him my 2021 iPad to replace that, and did the usual dance of backing up the old one to my Mac and restore the new one from my Mac. All went well, except now every now and then he gets a message saying:

Unable to restore

This item was purchased by a different Apple ID. Sign in with that Apple ID and try again.

Ideally, I would remove those apps from the device and reinstall them under his account, but I can't seem to figure out a way to find out which apps are causing the problem.

What I came up with was this:

• update all apps on his account
• log out of his account and into mine
• check for updates again
• at this point, I thought, the apps that can be updated are those connected to my account
• log out of my account and back into his
• delete those apps locally
• redownload them as him

except... nope. Ten minutes later, as soon as he woke the iPad up again, there was the message again.

I'm genuinely at a loss. I'm not even sure how it's possible that apps were ever reinstalled under my account, as I was careful to only use his credentials when I restored it. Still, not knowing which apps are causing this makes it impossible to fix.

I recall that back in the day one could simply provide the password as needed, and the system would save it. I'm pretty sure I'm not mis-remembering that because I distinctly recall creating a US-based Apple ID just to install a free app that wasn't available in Italy, and I was asked for the secondary account's password when updating my apps the first time after a restore (and never again).

Going through the list of Purchased apps on the device is an endless endeavor: especially in the case of my own account, I have literally hundreds of apps listed (the first purchase dating back to 27 September 2008). Further, it only allows me to filter by "All" or "Not on this device", whereas I would really need "Installed on this device" — that way, any installed apps would show up immediately.

Can anyone point me towards a way to get a list of currently installed apps, together with their "owner", or at least a list of currently installed apps by the current Apple ID user? It's not the end of the world, but it's annoying to get that message pop out out of the blue, especially when everything should be in order.

Thanks in advance!