Battery problem after MIUI 11 update

Admin of beta tester group has confirmed that there is battery issue in But many people have said that the battery life is same with MIUI 10 or even better than MIUI 10.
You can wait for next update or make a back up and do factory reset or go back to MIUI 10. You can go back to MIUI 10 by unlocking bootloader and using Mi Flash. Refer this thread for tutorial of unlocking bootloader and flash rom.