Xiaomi has opened up registration for MIUI 12.5 beta testing in China and the list of qualifying smartphones has been shared online. While it seems owners of the China ROM variants of the Redmi Note 7, Xiaomi Mi 9, Xiaomi Mi 10, and Redmi K30 can sign up, it seems there will be a wait ahead for Redmi Note 8 and Xiaomi Mi 10T Lite users.
https://www.notebookcheck.net/MIUI-12-5-beta-registration-opens-up-for-21-Xiaomi-and-Redmi-devices-Room-for-the-Redmi-Note-7-Mi-9-and-Mi-10-but-the-Redmi-Note-8-has-to-wait.512344.0.html