Xiaomi Redmi Note 8 global users should be receiving android 10 based on MIUI 12, well, another is update is available and currently rolling out in beta.
According to report, Xiaomi has released a new Android 11 based Miui 12.5 closed beta update with version 21.1.12. The second MIUI 12.5 closed beta build released for Redmi Note 8.
If you are using a China rom and will like to try it out, you can download this build from the link mentioned below.
If you are using a global rom and you are yet to upgrade to the latest Xiaomi Android skin, MIUI 12, then you can go to settings>> about phone and check for an update.