I have driven Sammy flagships since the S3. One thing that they always do is suck battery. For instance, I have an unhooked T-mobile branded phone, REVVL 4 + I only use to "find my device" for my real phone. I can leave it on for a week in standby and STILL not have to charge it.
My S21 needs a charge usually at least twice a day. (I'm a former Android geek so have abt all the power saving measures I can on).
I'm also a power user and use my phone 12 or more hours a day at times. So that's got a bit to do with it.
But Sammy flagships have always been hogs. I still love em though. I know they have abt a thousand functions I'll never use, but dammit, I like to know they're there. Never know when someone might ask you to calculate pi to the 3,328th place 🙄😜✌️