While Apple doesn't allow others to track users across apps, they themselves can do it because they have a monopoly on app store so it doesn't count as third party data.
That's shady....
Also: There is a HUGE difference (in my opinion) between Apple recommending me other apps based on the ones I already have installed vs Facebook tracking my presence and activity everywhere around the internet.
Personalized ads in Apple apps such as the App Store and Apple News help you discover apps, products, and services that are relevant to you. We protect your privacy by using device-generated identifiers and not linking advertising information to your Apple ID. Turning on Personalized Ads increases the relevance of ads shown by letting us use data like account information, app and content purchases, and where available, the types of News stories you read. Apple does not track you or share your personal information with any third parties.
Then a button that says “Turn On” and one that says “Turn Off”.