IIRC, for example phone keyboards use federated learning, where the model is further trained locally. You don't want to send every word the user types, for priv

IIRC, for example phone keyboards use federated learning, where the model is further trained locally. You don't want to send every word the user types, for privacy reasons and others. Some kind of "diff" of the local model can then be sent to the cloud at some time to add up to the base model. There is still an attack vector, you can infer a bit from the "diff", but you probably can't tell exactly what the user wrote.