The Stable update OS4.0.5.0.XPNCNXM has been officially released for Xiaomi 18 Fold (codename is lhasa). 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: Xiaomi 18 Fold ROM Topics Xiaomi Devices Index
Download Xiaomi 18 fold (lhasa) China HyperOS OS4.0.5.0.XPNCNXM Recovery ROM with Android 17.0. Firmware size is 10.4 GB.