I don’t know if this is a bug or intended as a “feature” in Strapi v4, but the REST API doesn’t seem to include the relations and components used in a collection when it is returned. The attributes returned by default only include the direct fields, but if I add “?populate=*” to the path the relations are added. However, components are not populated with their data, instead it only responds with the id used in the mapping table for the associated component, not any actual data. Finally, there is no indication in the default response that the collection contains relations, e.g., the “Author” field pointing to users is not even included in the response so there is no way to tell what relations you may want to populate unless you first populate all relations to figure out what’s in the model.
Let me know if this is a bug that I should raise as an issue on GitHub instead and I’ll do that.