Below are the challenges with PageFactory:
No of Pages: If there is an application with hundreds or thousands of web pages then the time and the effort in the development of automation framework will be high.
Maintenance Overhead: The cost increases when maintenance overhead increases which are due to the maintenance of large class as they break the OO design principle.
Programming Best Practices: The development of POM framework for multiple pages is equal to developers work thus testers should be highly knowledgeable in programming best practices.
Not Generic Model: Page object model is not a generic model and its specific to the applications.
The best approach to overcome the above challenges is by refactoring the POM concept to Screenplay Pattern.