Java: Composition vs Inheritance

They create tight coupling and make it difficult to change or extend behavior.

Deep inheritance hierarchies can make code brittle because they often involve a tight coupling between classes. Each subclass depends on its parent class's implementation, which can become a problem when changes are needed. For instance, if a 'BaseProduct' class in an e-commerce application has subclasses like 'DigitalProduct' and 'PhysicalProduct', any modification in 'BaseProduct' can inadvertently affect all its subclasses. This can cause unexpected behavior and make it challenging to introduce new features without risking existing functionality.