The Mi Mix 3 may have been overlooked by Xiaomi for Android 11 after one OS upgrade
The Mi Mix 3 may have been a flagship smartphone, but it has received sub-part software support since its release in 2018. The device may have been upgraded from MIUI 10 to MIUI 12 in the last two and a half years, but it was one of the last devices that Xiaomi brought onto MIUI 12. Two MIUI upgrades have not coincided with two Android OS updates though, as the Mi Mix 3 remains on Android 10, having been released on Android 9.0 Pie.
Xiaomi has not included the Mi Mix 3 in its MIUI 12.5 plans yet, too. According to a Mi Community moderator, Xiaomi has provided no information about testing Android 11 on the Mi Mix 3, either. Likewise, Xiaomi has not published a new China Beta build for the device since September 2020.
Hence, it seems that Android 10 could be the last stop for what remains the most-recent device in the Mi Mix series. Fortunately, communities like those on the XDA Developers Forums are on hand to bring the former flagship onto Android 11. ArrowOS 11.0 is one of the most popular ROMs for the Mi Mix 3, but you must unlock your device before switching from MIUI to any custom ROM. You can find out how to unlock the Mi Mix 3 here.