You can try alternatives:
https://forum.xda-developers.com/mi-pad-4/development/paranoid-android-pie-beta-mi-pad-4-t3903349
https://www.getdroidtips.com/mi-pad-4-android-9-0-pie/
http://theupgradeguide.com/2019/07/28/install-android-9-0-pie-on-xiaomi-mi-pad-4-lineageos-16-how-to-guide/...