Hi!
9.6.20 android 9 was still.
20.1.2 newest release android 10 working on my mix2s smootly.
Before install:
- in fastboot mode flash newest twrp from
https://twrp.me/xiaomi/xiaomimimix2s.html
- back main android apps (e.g. android system webview, google play, google services, google app) to system app
- from settings -> my phone (1. row (I use Hungarian language)) -> storage and clear cached data.
Install:
- reboot to recovrery and make backup recommended
- if use magisk root first uninstall with magisk uninstall (because after - new rom installed bootloop error occured)
https://forum.xda-developers.com/apps/magisk/official-magisk-v7-universal-systemless-t3473445
- clear dalvik cache only
- flash newest xiaomi rom
- reboot phone
- Try all apps, if problem any system app after flashing, clear application data, or must be restored to the system application
(I experienced the same problems during the transition Andoid 9 -> 10)
- if use magisk then install it