Xiaomi unveiled its MIUI 12 in China in April, followed by a global launch in May. Now, the first set of devices have started receiving the stable beta firmware. This is normally the final stage before the update begins seeding to retail units. These include the Xiaomi Mi 9, Mi 9T/Mi 9T Pro and the Redmi K20/K20 Pro. Owners of these devices will have to enroll through the Mi Pilot program for which you can find more details here. These builds are still not recommended to install on your daily driver as some unexpected bugs may appear, but should be perfectly stable overall. That...
Source: https://www.gsmarena.com/miui_12_stable_beta_arrives_for_xiaomi_mi_9_mi_9t_and_k20_series-news-43552.php