Hello MIUI Fan's!
Today you'll know why on some device you can't lock bootloader. In 2018 year Xiaomi change police for lock bootloader, and all model 2018+ have this new policy.
If you have Device for China (China version), don't Lock BOOTLOADER on this Device after flashing Global ROM, same with GLOBAL Device and China ROM. If you Lock it, Device will be always boot into MI Recovery 3.0 and show you Red Message "This MIUI version can't be installed on this Device". For restore such Device need use EDL (but for now EDL also need permission, you can't flash it without permission). Now all new Device have this Policy
Here i write all model 2018-2019 years. Be careful!!
If there is an inscription GLOBAL or box is completely in English - this is the global version. But if box without such an inscription and all in Chinese is the Chinese version of the device. If you lock the bootloader on it while being on any other rom that the one it originnaly shiped, you will get this message below.
Thanks to all!
Thanks to Administrator @Elaine2046