It is a China model. The model is M2102K1C. The Global variant ends in G (M2102K1G). Just flash 12.5.7 and select the re-lock button on the lower right corner of the MiFlash tool. It does a complete format of your storage. It totally wipes all partitions. However, I'm sure if they spend several thousands of dollars, they might be able to detect through forensics that there was something else there. But it really doesn't matter, because Xiaomi allows bootloaders to be unlocked, it doesn't void your warranty.i've actually addressed this above.
thanks for your reply,
my concern is not really to make sure that it's a CN model phone or not.
but my question is about the A/B partition when relocking.
yes i know this phone came with CN rom as stated by seller and i can confirm it myself, first boot, all chinese, some parts of the box are in chinese, no charger in box, and the device model is M2102K1C.
if you read the steps that i did, at 1 point, i boot TWRP via fastboot and flashed mi.eu 188.8.131.52 rom, twice even.
before i reverted back to 184.108.40.206 CN rom via fastboot miflash.
now to relock, i have to be absolutely sure no trace of mi.eu rom? is it still residing in inactive slot (because of AB partition), which will brick my phone when relocking even when official CN rom active slot?
that's what i want to know.
one thing i know is, if i relock bootloader with a rom not originally made for that device (custom rom or other region rom), it'll cause a brick.
i know i'm on the CN official rom that came with the device, but what about the inactive slot? will it affect the relocking of bootloader that can cause a brick? this is what i'm not sure of