A financial institution has deployed a machine learning model using Amazon SageMaker to predict whether credit card transactions are fraudulent. To ensure model performance remains consistent, the company configured Amazon SageMaker Model Monitor to track deviations in the model accuracy over time. The model's baseline accuracy was recorded during its initial deployment. However, after several months of operation, the model’s accuracy drops significantly despite no changes being made to the model. What could be the reason for the reduced model accuracy?