For a couple of months, Apple has been rejecting apps that don't comply with its Advertising Identifier (IDFA) rules, and it has recently added a new section to iTunes Connect that makes the rules and process more transparent. Now, when developers log in to iTunes Connect to distribute or update apps, they see language which explains that the IDFA is "the only way to offer targeted ads." Also, developers who are using the IDFA must check boxes to indicate how they are using it and to state that they allow users to opt out of ad tracking.
Some have questioned whether Apple will really be able to enforce its IDFA rules. However, the new language in iTunes Connect makes it clear that mobile development firms could find their apps kicked out of the App Store if they don't comply.