I don't know but I'm getting the same battery life since I've switched again to weekly (8.8.x). The best battery life I had on 9.5 stable but since then it got worse but not a whole lot. Like, I'm getting 6-7h SoT on Wi-Fi and about 4-5h SoT on LTE/mixed usage. The worse was on stable, 10.0.4/5 where I couldn't get more than 4-5h SoT on Wi-Fi or 3-4h SoT on LTE/mixed.
The only reasonable answer is... try yourself.
My case (Mi Mix2S): I was able to install 8.8.X (xiaomi.eu dev branch), then 10.0.0.3 (xiaomi.eu stable branch), then again 8.10.25 + 8.11.1 ((xiaomi.eu dev branch) without wiping data and everything worked flawlessly. Instead I was not able to move from 8.10.25 to 10.0.0.4 (stuck on PIN code screen). Many users experienced bootloops doing the very same steps. So it totally depends on your setting and apps.
I would suggest to make a backup (and copy it to an external storage) and then try to wipe dalvik + cache and dirty flash.
In case of issues, you can wipe everything, flash and try to restore the backup.
In case of issues, you have no other option than clean flash.