Apple App Store Denial Because of Apple Pay

We have an app that we're getting ready to release. It is a web-first app where users register for the application and purchase their subscriptions via the web app. We are also developing browser extensions for all of the major browser platforms, including Safari. We are also going to have an iOS app.

Apple has denied our browser extension because we do not support Apple Pay for in-app purchases of "premium content". To be clear, the only "in-app" purchases that we have are the subscription to the platform, which is carried out only on the web app, not in the other planned platforms.

There are many applications in the Apple App Store (e.g., Dropbox, etc.) that have mobile apps and browser extensions and use their web app as the platform for initiating and maintaining subscriptions and the iOS / Safari extensions only allow access to those services. What are we missing in presenting this to Apple for approval? I don't want to end up with the mess that LinkedIn has where you can purchase a subscription as an in-app purchase via the iOS app and the subscription becomes completely unmaintainable outside of the Apple ecosystem.

Thanks in advance for any guidance.