For repository pattern, is it a good/bad idea to have a list/collection of entities as member variable that the methods act upon.

Below is high level logic ex. of one way vs the other. What reason(s) would you choose one over the other?

class ProductRepository { List<Product> productList;

public List<Product> GetProducts() { return productList; } 

}

vs

class ProductRepository { public List<Product> GetProducts() { return dbContext.Product.Query(); } }