Juice Overload

Chris works at a juice-packing company where he uses a machine-learning model to predict the demand for different juice flavors.

After training and evaluating the model, he was confident that it was ready for production. The model was deployed, and the company started using it to plan its production and distribution.

During the first few months, everything was working as expected. But then the company noticed that the model consistently overestimated the demand for certain flavors.

What could be the cause of the problem with the model?