In 2019, Mozilla called on Apple to increase user privacy by automatically resetting the Identifier for Advertisers (IDFA) on iPhones. The IDFA lets advertisers track the actions users take when they use apps – kind of like a salesperson that follows you from store to store while you shop, recording every item you look at. Creepy, right?
https://foundation.mozilla.org/en/campaigns/apples-anti-tracking-plans-iphone/