6211594550 replied at 2020-11-28 22:31:19
If you have unlocked your bootloader you can downgrade using the MiFlash utility and the complete ROM package, otherwise you can't.

i think my bootloader waslocked, i actually went to a computer technician and he will tell me in a few days if he can downgrade it(i didn't attempt it because i read about ARB , i was a little afraid ) but if he doesn't fix it ,i will attempt on my on. I have already downloaded Mi flash tools, and a previous MIUI ,but i haven't reaserchedyethow to unlock bootloader. Is it difficult?