The MIUI 12 rollout for the Global variant of the Redmi Note 8 has been stalled. Apparently, there has been an issue reported with the OTA (over the air) process that is preventing the Android 10-based MIUI 12 update from reaching owners of the Xiaomi Redmi Note 8. It's unknown how long a fix for this issue might take.
https://www.notebookcheck.net/Redmi-Note-8-MIUI-12-update-rollout-partly-stalls-because-of-OTA-issue.502700.0.html