Wait - why not? Apple controls iOS, they control the sandbox apps run in. Of all protections, app tracking seems like they aren't really fixing the problem by using monopoly power and threatening to pull apps.
The entitlement is enforced by legal contract. The only thing stopping Meta from blatantly ignoring this policy is the fear of consequences by Apple.
Apple can absolutely make API changes to prevent tracking. They could implement DNS blocking as part of the DNS lookup API. They could add a toggle that requires the user to whitelist any network connections. They could do analysis and provide users reports of which apps they think are doing tracking, with options to disable whichever feature they think is accomplishing the tracking. They could add temporary grants (i.e. "allow network access for the next 15 seconds").
Hell, Apple doesn't even need it's own app store to threaten Meta. They can blacklist binaries and network connections at the OS layer.
Apple likes this setup because they remain the gatekeepers of users, which is extremely profitable.
Try it on iOS, if you don't have the right entitlements system API calls will fail.