I bought my S5 last Friday and the battery sucked since day one. For exemple, it is exactly 39% right now. It was 100% 9:30 HOURS AGO. I used it normally, didn't even track exercises... Terrible!
But I must say, this is not watchOS 7. It's like that since my full 4 days on watchOS 6.
So I came here to this forums to see what people thought about S5`s battery. It seems like the first month or weeks battery is always bad. But after this period it can actually go up to 18h of usage as apple claimed.
Maybe that's what's happening right now with all of you who updated, I don't know.
I hope my battery life improves, cause getting only 11 hours on a device who promises to go up to 18 is really frustating.