Apps that pull in, embed, or build functionality around another company's site, API, or product beyond a standard public API need to show they have permission from that third party — Apple may ask for a letter or written authorization.
Commonly triggered by apps that scrape or wrap another company's website or service without any formal agreement in place.
"Your app integrates content or services from a third party, but we could not confirm you have appropriate permission to do so, per guideline 5.2.2."