REST says nothing about normalization. In fact the opposite — a resource representation in REST is the very same thing as a graph in GraphQL, or a view in SQL:

REST says nothing about normalization. In fact the opposite — a resource representation in REST is the very same thing as a graph in GraphQL, or a view in SQL: an arbitrary remix of underlying data. REST is meant to be a projected view-model layer for web clients to interact with underlying data through; it's not meant to inform or be strongly bound to the shape of that underlying data.