Xiaomi's latest build of MIUI 11 for the Mi 9T and Redmi K20 may be re-issue Android 10 to both devices, but there have also been reports of the update causing heavy battery drain for some handsets. There is a workaround though, with some Xiaomi software potentially being at fault.
https://www.notebookcheck.net/Android-10-builds-of-MIUI-11-may-cause-high-battery-drain-on-the-Xiaomi-Mi-9T-and-Redmi-K20-but-there-is-a-workaround.451770.0.html