Start from May 2018, Huawei doesnt allow their users to unlock thier phone's bootloader. I mean like: why????! Other manufacturers, they just allow their users to unlock their phone's bootloader for development or enjoy special features. Even Xiaomi doesn't do that: they just set a duration of 360 hours grace time, after that period then users are allow to unlock bootloader. Why Huawei wants to restrict development?

Here's the news:

https://www.xda-developers.com/huawei-stop-providing-bootloader-unlock-codes/