"When tools like connected experiences evolve, even if the underlying privacy settings haven't changed, the implications of data use might be far broader," Owens said.
A spokesman for Microsoft wrote in a statement to CNBC that Microsoft does not use customer data from Microsoft 365 consumer and commercial applications to train foundational large language models. He added that in certain instances, customers may consent to using their data for specific purposes, such as custom model development explicitly requested by some commercial customers. Additionally, the setting enables cloud-backed features many people have come to expect from productivity tools such as real-time co-authoring, cloud storage and tools like Editor in Word that provide spelling and grammar suggestions.