Family Sharing - Voice Memo's shared without permission!

We had a small family crisis. We recently upgraded our phones to iOS 13 (we don't know if this is connected or not), and one of children was suddenly able to hear voice memo recordings on their phone made by us on our phone. iCloud had been used to back up and share recordings on my wife's devices, but as far as I can see, there's no option to share recordings automatically via family sharing.

So how did our child suddenly have access to the recordings on their phone? They don't know any parental passwords etc. These were recordings of discussions not suitable for our children, and have caused major issues.

Any idea if there's some hidden setting, or has something gone wrong with iCloud?