This is absolutely not true. DeepSeek is most famous for publishing really in-depth papers on their training process but the other labs have started to do the same as well.

If by "training corpus" you mean the actual data I already acknowledged that that's currently legally impossible.

In fact everything I just said I said in my original comment. It's like you didn't read it at all.

DeepSeek's GRPO Infrastructure, multi-stage training pipeline, and their "cold start" phase have been massively influential in LLM research.