How can MIUI read my previous MI Account ID and phone number on clean install? I unlocked my bootloader, flashed some custom ROM and the ROM is working fine for several months.  Today I decided to return to the stock MIUI global ROM.  After finished flashing new images using fastboot, I'm quite surprised when the phone asked me to login to Mi Account.  It remembers the account id and my previous phone number correctly.  This is when I'm not connected to Internet.  I also have flashed TWRP  cleared user's data many times before. 

I would like to know where is this information stored?  Is it on /persist partition?  Or, perhaps in Trusty OS?  Is it possible to see what are stored there (apart from account id and phone number)?
For Mi 8 Lite, it is stored in /persist/fdsd/st. This file contains JSON structure with extra_email and extra_phone that matches what is displayed in the screen.  Also, after deleting this file, the initial setup step that asks for account activation is not displayed anymore.