How to report competing app which has bypassed In-App-Purchase and started using third party payment processor

I have an App that sells subscriptions to access video content (similar to Netflix). When I tried to launch with a third party payment processing tool, Apple blocked my app until I've integrated In App Purchase and completely removed the third party payment processor. A competing app offering the same exact service, however, has launched with In App Purchase. On a later update, the competitor removed the In App Purchase option and replaced it with a third party payment processor. The competing app, according to App Store rules, is in violation of removing In App Purchase despite selling a purely digital service. How can I report the competing app to Apple so that they would level the playing field? The competing app to have a 30% price/cost advantage as they don't have to pay the Apple Tax. Any answers truly appreciated <3