Customers often asks me where their identity data is stored exactly.
So in general you know that most identity data stays in the region where your tenant is created but some attribute are synchronized anyway to the US regions.
“Some” ? But which one exactly ?
There is a document from Microsoft that clears up that:
Where does Microsoft Azure Active Directory (Azure AD) store identity data for European customers
The following identity-related attributes will be replicated to the United States: