Big Sur 11.3 battery drain MBP M1 - Apple support didn't lead anywhere.

Ever since 11.2.3, I was basking in the full day battery life working from home on the M1 Mbp. However, moving to 11.3, I literally can see the percentage drops every 10 mins or less. Yes - I was in contact with apple support, none were able to figure it out.(counting 3 support reps) I never changed my work routine post update and also uninstalled chrome! as well as dropbox since they were hogging memory in 11.2.3. Firefox indeed hogs memory but It was doing that in 11.2.3 and I still was getting 12 hours+.

All apps updated and battery shows 100% health. One issue was apple diagnostic freezes, so I cannot run that.

I wish I could go back to 11.2.3 and maybe factory reset of laptop might do it for me. It means backing up 200gb of files first and all that work.

E.g. This morning the laptop was at 70% at 9am and its 1030am and down to 55%. All I have been doing is outlook, safari, Firefox and few word edits, Teams is open, mail. etc.

Any advise please and thanks!