@WunDaii same for me, it looks fixed right now. I received a response saying, 'Investigation complete - Unable to diagnose with current information,' but it seems like it was a general issue, so they likely fixed it for all users.

@WunDaii unfortunately no solution yet. I've also filed a report on https://feedbackassistant.apple.com/feedback

Same here

The issue was resolved by setting correct subscription levels Subscription levels: A ranking system of subscriptions within a subscription group that determines the upgrade, downgrade, and crossgrade path available to subscribers. Levels make it possible to offer varying access (basic, premium) of the same service. https://help.apple.com/app-store-connect/#/dev75708c031