Most likely, MIUI 12 will be the last major update for these interesting models
After updating its current generation flagships and mid-range smartphones to the MIUI 12 stable version, Xiaomi has begun rolling out updates for budget smartphones and older flagships.
Xiaomi Mi Mix 2S and Mi Mix 3 also received stable MIUI 12
As reported by users of Xiaomi Mi Mix 2S and Mi Mix 3, they have already started receiving the stable version of the MIUI 12 firmware. According to the traditional scheme for Xiaomi, the update was initially made available to users in China. If they do not reveal any critical errors, then soon the firmware will be released in the rest of the world.
Xiaomi Mi Mix 2S out of the box ran MIUI 9 shell based on Android 8 Oreo out of the box. Xiaomi Mi Mix 3 debuted with MIUI 10 based on Android 9 Pie. Prior to MIUI 12, both devices were running MIUI 11 based on Android 10.
This means the MIUI 12 stable update is respectively the third and second MIUI update for these phones. Unfortunately, according to the official listing, none of these phones will be updated to Android 11. It is also unknown if they will receive MIUI 13 next year.
Most likely, MIUI 12 will be the last major update for these interesting models.