I'm saw a similar issue in the M1-MBP. What I discovered is that the problem was Chrome. Chrome for M1 uses power like crazy. I was getting 30% of the advertised battery life. So, last night, I tried a test and shut down all chrome instances and used nothing but safari for browsing. That was 8 hours ago. My browser ran all night (cuz I fell asleep watching YouTube with autoplay on). My battery is at 87%. Based on the hype this is what I would have expected. Oops and I left Activity Monitor running all night too. FYI it's using 3-4 times the "energy" of safari.
I suspect that chrome did a recompile for M1 but did not optimize or refactor their code for power efficiency. First a memory hog now a CPU hog.
Because of this, until Chrome is optimized I'll only open it when I need to for G Suite apps or password migration etc. Been looking for a reason to move off Chrome anyway.
Please try using the native safari browser. I'm going to download Bing and see if he's been optimized for power consumption by MSFT.