Xiaomi recently announced that it will be shutting its Global Beta ROMs for all devices, with effect from July 1, 2019. Public beta ROMs, though are presumed to be Beta in nature, have been stable enough for a lot of users to use it as a daily driver mainly because of the rather frequent nature of updates. This came with the drawback that a lot of these users would not provide feedback to Xiaomi through the relevant channels, defeating some of the purposes of the program and living with a not-so-stable MIUI experience. Now, Xiaomi is looking for a closed group of beta testers who wish to try out the upcoming Android Q update to the Poco F1, as well as Android Pie updates to the Xiaomi Mi 6, Xiaomi Redmi 6 and Xiaomi Redmi 6A.
This recruitment drive is for testing out "Stable ROM" and making it "more perfect" before releasing it publicly, which does practically make it a beta test. The thread further goes on to call the version "unstable" and "nightly", which does indeed make this a beta test despite the nomenclature adopted for the program.
Testers for the Poco F1 will try out the Android Q ROM for the device, but it is unknown whether this refers to Developer Preview variants of Android Q, or MIUI-based Android Q, or even stable Android Q but on MIUI (though this would be far-fetched considering there is still plenty of time for stable Android Q to release).
For the Xiaomi Mi 6, testers will try out the Global Stable ROM for its Android Pie release, which was made available in Beta form previously. Similarly, alpha builds for Android Pie were available previously for the Xiaomi Redmi 6 and Xiaomi Redmi 6A, and now Xiaomi would be testing out what would become the Stable releases.
Xiaomi Redmi 6 XDA Forums | Xiaomi Redmi 6A XDA Forums
Application deadline for all the above testing groups is July 7, 2019. Testers need to know English and should be comfortable using QQ as their IM tool. You would also need an unlocked bootloader, and should be willing to bear the risk of a broken update. If you are interested, follow along the other instructions in the application thread to apply for the same.
Source: Mi Community