Well, I have a first and last Xiomi phone. Worst than Samsung move.
Tldr: you are not buying a phone, you are renting it from them.
You have to use their external service to unlock the bootloader, up to one time per year. No more.
And that’s still better than most phones offer: https://github.com/melontini/bootloader-unlock-wall-of-shame
They’ve been a shitty company for years now, so this is not surprising
While earlier Xiaomi allowed users to unlock up to three devices per year, the new policy brought that number down to a single device per year and applies to both China and the rest of the world.
Given that it’s per user, you can probably sidestep this shit by creating a new xiaomi account when you get the phone, as you’re likely going to flash a custom rom to get rid of the endless bloatware that they do their best to reinstall every update.