DeepSeek (which GRPO was invented for) still uses a normal English CoT to this day. (V4 Pro) They had to alternate with supervised learning because RL is just very very hard and GRPO is incredibly weak compared to supervised learning. They aren’t deliberately sacrificing performance by forcing an English CoT instead of a more useful or efficient neuralese. They are forced to do it because RL just doesn’t work that well.
DeepSeek (which GRPO was invented for) still uses a normal English CoT to this day. (V4 Pro) They had to alternate with supervised learning because RL is just very very hard and GRPO is incredibly weak compared to supervised learning. They aren’t deliberately sacrificing performance by forcing an English CoT instead of a more useful or efficient neuralese. They are forced to do it because RL just doesn’t work that well.