can you help me to downgrade ? should i download recovery / fastboot or ota?

[mantras]

hi
i would like to downgrade to the last miui version for my phone was 14.0.9.0 europe

the last firmware i found it's MIUI 14.0.5.0.TNFEUXM and there is recovery version , fastboot version and ota

for what i understood to upgrade i have to use recovery version
to downgrade fastboot?
my phone is a redmi note 13 pro 4G

about

Requirements:

Your device's bootloader must be unlocked.

can i after lock the bootloader?
https://xiaomi.eu/community/threads/miui-14-stable-release.67685/i read the tutorial here
thanks