> Do you know of any university that host Deepseek?

https://chat.zju.edu.cn

https://chat.sjtu.edu.cn

https://chat.ecnu.edu.cn/html/

To list a few. There are of course many more in China. I won't be surprised if universities in other countries also self-hosting.

Where does it says that it is self hosted? And why it is exposed to public.

They are self-hosted and require campus credentials for access. If you try to chat with the ZJU instance, it will redirect you to a login page. ZJU is unique in that it appears to support access from all higher education institutions in China.