Barbara Krasnoff, The Verge:

In 2019, an article in The Washington Post by Geoffrey Fowler described the author’s shock when he discovered just how many of his iPhone apps were collecting and uploading information about his usage while he slept.

And:

As Fowler’s article demonstrated, iPhone users are not immune to this. Since his article was published, Apple has made some laudable changes to its privacy policies. But it’s still a good idea to take charge of your own data. There are some simple ways to minimize the amount of tracking that app vendors can do and the amount of data they can access.

The whole article is worth scanning, just to get a sense of all the options.

But note that things are changing, and will continue to change. For example, there’s a new setting in the iOS 14.5 beta at Settings > Safari > PRIVACY & SECURITY called Privacy Preserving Ad Measurement, which is enabled by default.

Read the Verge piece (headline link), and read this post about Privacy Preserving Ad Measurement.