Not sure if battery saver helps ?
I never use phone for gaming. Only works related and light entertainments.
I so far can last 2 days before recharge on 12.0.8
Appreciate you guys who upgrade to the latest stable and report bugs.
I also tempted to upgrade to 12.1.3 after I flashed my phone with 12.0.8. Luckily I found this thread which save me from all the hassles