Hi. I have Redmi 9T with, you know, horribly optimized MIUI 12.5.12. With MIUI 12, phone was wery smooth, but after 12.5 everything changed. So, I tried to downgrade it to MIUI 12 via updater app but that is officially unsupported. What can I do? Is it worth to wait more for long awaited MIUI 13, or go back to 12 (with flashing, or fastbooting, I don't know that well)? And if I'll do flashing, can I do without backup and in-phone data and media loss? There should be a solution. 
