In Principles of Macroeconomics (a free ebook available on openstax), the chapter on inflation says, regarding deflationary recessions:
High levels of unemployment typically accompany recessions, and the total demand for goods falls, pulling the price level down.
So, a lower quantity of a product demanded leads to a lower price for that product. But the law of demand says that a lower quantity of a product demanded leads to a higher price for that product.
It appears to me as if this is a contradiction.
Perhaps I am misunderstanding what “lower quantity of a product demanded” means. Perhaps this means that the demand curve is shifting to the left and hence lowering the competitive price (the price reached at market equilibrium).