Xiaomi has officially announced that the MIUI 12 beta stable update (V12.0.2.0.QFJINXM) has started to roll out to some Xiaomi Mi 9T/Redmi K20 devices in India. The firmware has now been pushed OTA and users chosen by random should start receiving notifications to install the MIUI 12 update. The public ROM should be available soon.
https://www.notebookcheck.net/MIUI-12-beta-stable-update-made-available-to-random-Xiaomi-Mi-9T-Redmi-K20-devices-in-India-ahead-of-planned-public-rollout.479587.0.html