Comment by sneak
10 hours ago
> While this has left a long tail of inconveniences, many resolved and some not, I am very confident that using 1 app on my iPhone/iPad will not leak data to another in any case that I am likely to care about as a non-significantly interesting person (political figure, etc).
Log in to YouTube with one Google account. Log in to Google Drive with a different one.
Google knows that both accounts are owned by the same person, because Apple lets Google's apps access the data of the others on the same system.
I don't think it's something special that Google is doing. I suspect they are just using the built-in App Groups functionality.
Basically, it's a way for different apps from the same developer to share information via a data container.