The email only talks about "non-consumable in-app purchase assets", not about "non-consumable in-app purchase content". To be honest, I've never heard of an "in-app purchase asset" so maybe that's something different than what I use in my app. What just makes me wonder is that nowhere in the documentation for the StoreKit API that I use does it mention that there will soon be no more Apple hosted IAP content. See the section "Download Hosted Content from Apple’s Server" on https://developer.apple.com/documentation/storekit/original_api_for_in-app_purchase/unlocking_purchased_content

On the official App Store Connect Help you can read under the link https://help.apple.com/app-store-connect/#/dev3cd978dbd still (as of March 13, 2022): Non-Consumable: A product that is purchased once and does not expire or decrease with use. Example: Race track for a game app. Apple can host your non-consumable products for you. I think it's time to point out the planned changes that will come into effect from April 2022. Thank you.

Aha. That's right. I had assumed there was a new link that was different from the previous one. But the only difference is that you can no longer find the app via search.