Hello every body, after many painful days, I got 72hz on MIUI 12.0.3 India. I can share with you my steps as belows:
From the latest MIUI 12.0.3 India
1. Flash OrangeFox via ABD Fastboot command
2. Flash Magisk via OrangeFox (to root your device)
I got litte bit stuck in this step, please search gooogle how to get magisk boot img
3. Flash Immesity kernel for k20 pro via OrangeFox (choose latest "MIUI12" ver 08.09.20)
4. Install RR app (chinese apk) https://www.coolapk.com/apk/com.rise.rr
Then apply 72hz, it's more stable than 75hz.
5. Edit build.prop set "ro.fod.dimplayer.enable = false" to fix fingersprint.
6. Hide magisk to use banks app (
7. About green tint, use app Color changer Free apk, reduce green to 240, red to 250.
All done. There is some difficulty in each above steps, but after all It's so wonderful.