What you're seeing here might also be due to the "catastrophic forgetting" problem: as you're teaching the model about your new entity, it's overfitting on the data and "forgetting" what it had previously learned. So if you care about the other entity types, a simple solution is to mix in entities that the model previously recognised correctly. This is pretty easy to do with both Prodigy and spaCy. You can find more details and strategies in this thread: