The Closed Beta / Nightly update 21.12.7 has been officially released for Redmi K40 / Mi 11X / POCO F3 (codename is alioth). 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 MIUI or HyperOS 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: Redmi K40 / Mi 11X / POCO F3 ROM Topics Xiaomi Devices Index
Download Redmi k40 (alioth) China MIUI 12.5 21.12.7 Recovery ROM with Android 12.0. Firmware size is 4.5 GB.