Why is my iPhone registered in my Google Account Permissions?

Question

Having realized that I was still using app-specific passwords for my Gmail account on my devices, I just switched to OAuth. I had a look at my account permissions which showed the following:

The bottom item was created just now after re-adding my Google account in the iOS System Settings using OAuth.

But what's the iPhone item?

When I click on it, the sidebar says my iPhone has full access to my Google account and it was authorized on April 21st. That's not too long ago, but unfortunately I can't remember what I did on that day.

According to the "Learn more" link, some apps (e.g. some Google apps) might have full access. It also specifically mentions iPhones and Android phones, but it does not say why they would appear here and what causes them to show up.

What is this item, and why did it appear?

Is it safe to revoke access?

_{After all, I have properly set up access for iOS now.}

Answer 1

After revoking access as suggested by Al E., I figured it out.

I had installed several Google apps recently. I was surprised to see that after signing in with the first app (YouTube), all other apps were suddenly aware of my account, so I just had to select it without entering any credentials.

After revoking access for this iPhone item, my account was completely gone from all apps.

So what this means is that when you sign into your Google account using a Google app, they store some reference or identifier of your phone online. That way, when you install another Google app, they can simply check their database whether there are any accounts associated with the phone and present them to the user. Which means the user doesn't have to enter their credentials for every single app.

Answer 2

It's easy enough to re-authorize if necessary, so I'd simply revoke access and then see what the iPhone complains about.