Thanks for jumping on this so quick.
By the looks of it, you’ve understood what’s going on but just to clarify again:
Apps on the DO app platform can not be added as a trusted source for the managed database, resulting in the DB being accessible by anybody. This is obviously terrible, but also against GDPR assuming your app is storing any user data, which you are if you’re managing user accounts.
Providing the DO contacts get back to you, could you please provide an update? It’s a real shame this has came to light as I was starting to like the App platform.