Apple Music Why does my own Apple music playlists from MY Apple ID keeps getting synced or merged onto another person's Apple ID, despite never making playlists?

[SpaceCrystal]

Greetings. I sometimes happen to borrow a relatives' iPhone 12 Pro Max, & took the time to sign out of her Apple ID, while signing onto my Apple ID. Sometimes, I would buy music from iTunes, & use it to make my own music playlist on Apple Music.

Here's the problem: Sometimes, whenever I sign out of my Apple ID, then sign back into her Apple ID (followed by the old passcode), all of a sudden, everything that I have going from my music & my playlists happens to be synced/merged onto her Apple ID account, despite her never purchasing anything from iTunes or making any music playlists whatsoever. And we don't use either Home Sharing or Family Sharing.

Is this a bug? How do I fix this problem? We have iCloud, by the way.

 

[0128672]

I could almost swear this issue has come up before in the forums, and although I searched for it for a few minutes, I can't find the previous thread.

If she's not using the app, couldn't she simply delete it? Or turn off Show All Purchases in settings?

If you have a Mac, you can manage devices that have access to your content. To do that from the Music app on a Mac, go to Account > Account Settings > Downloads and Purchases > Manage Devices. If her phone shows up on that list, you can remove it.

 

[SpaceCrystal]

We don't have an iMac; Just iTunes For Windows.

I've even tried deleting the app & re-installing it on her phone, yet, everything that I have on Apple Music from my Apple ID account is still appearing on the Apple Music app when it's on her account whenever I hit "Library."

I also happen to have iTunes Match as well.