SOLUCION: your device is corrupt. it can't be trusted and may not work properly Xiaomi Redmi Note 9
Download Center
Xiaomi Drivers on your PC
https://xiaomifirmware.com/downloads/...
You must restart your PC after installing the drivers for it to be effective. Otherwise, your Xiaomi will not be recognized in fastboot mode.
Codes
fastboot devices
fastboot --disable-verification --disable-verification flash vbmeta vbmeta.img
fastboot flash vbmeta vbmeta_system vbmeta_vendor Remove checksum files
fastboot reboot