A few other things you can do to reduce battery drain.
1. Turn off screen auto-rotate
2. Turn off mi cloud sync
3. Turn off xiaomi interconnectivity
It's still higher than the older miui but now my battery can last over 12 hours at least.
My device is a 2 year old Mi 11 Pro on HyperOS xiaomi.eu.
First remove your screen protector if you have one installed.
You could try downgrading to last miui 13 stable .
Flash using fastboot and do full wipe.