going to say something totally baseless and crazy but.. i used to get 4h 30m screen on time (on 4g) when i was rooted with magisk on os2.0.3.0 on nuwa
the day before i did a clean install and did not flash magisk this time around, and today i got 6h 20m screen on time (on 1440p!, 4g only)... if you have magisk, try uninstalling it or clean flashing..
not to mention my banking apps just work without fuss thanks to the xiaomi.eu module too..
also my phone battery is quite depleted too, i have 430 cycles, will use it till one thousand then likely upgrade my phone, or change the battery.