I’m thinking just a banner along the top of the viewport with “Dismiss” and “Learn more…” buttons. The latter pops up a window with a small gray “More options…” link at the bottom, which invokes a modal with the options “Continue signed in as Alice” and “Manage Profiles…”, the latter of which allows you to disable syncing while simultaneously deleting all your local bookmarks and browser history.

These last couple of comments were probably some exaggerating pun... But after this story I was running privacy checkup, surprisingly found that my location history was on (after turning it off several times long before, which is a separate question why it turns on), turned it off again and then got 404 when trying to delete it. All this in a labyrinth of often circular links without much clue where the actual switch is.

(A year later) 'Over 90% of our users don't choose to turn these settings off. So we made on the default and removed the option.'

... We passed the point where dark UX patterns deserved the benefit of doubt a few years ago.

If it benefits the company, it's intentional.

This thread got progressively more accurate and more depressing at additional comment

Judging by all those post-GDPR popups I frequently receive the text would also contain some text like “by clicking ‘accept’ or ‘X’ you consent to XYZ.”

Theres almost never a true choice.

You don't have to click on 'accept' or 'X'...

I see where you’re going but that’s just not practicable, isn’t it?

Generally if the notification is getting in the way, I delete it from the DOM.