The Closed Beta / Nightly update 20.4.27 has been officially released for Mi Max 3 (codename is nitrogen). Before updating, please make sure you have downloaded the exact ROM matching your Xiaomi phone/tablet. In Fastboot mode, you can check model code by typing
fastboot getvar product in cmd/shell.
The firmware files posted here are all official Xiaomi ROM, xiaomiROM.com do not own and never modified those firmwares，you will always download the file from Xiaomi server.
You may interest in those contents: Mi Max 3 ROM Topics Xiaomi Devices Index
Download Mi max 3 (nitrogen) China MIUI 12 20.4.27 Recovery ROM with Android 10.0. Firmware size is 2.4 GB.