Series 7 seems to use more battery than the older Series 3. In my experience Series 3 used to leave me about 50-70% remaining after a full day of use, and my Series 7 is typically 30-60% from a similar day.
Your new watch seems to be using rather more battery than I would expect particularly when you start your day, and there is a noticeable change in the slope of the graph about 6am, which suggests extra load due to your usage. I have a few suggestions;
It is a new watch so it is still settling down after installing. Monitor for several days, and ideally at least a week before you decide if there is a real problem.
I understand it is a shiny new toy, but you need to be cautious about checking the screen every few minutes where it would be less frequent on the old watch. Screen wake-ups and activation use power!
If you have a day where you can just leave the watch off your wrist, off the charger and unused, it will give you a baseline of battery usage. I know it will be hard to be without, but give yourself a leisure day at the weekend?
I was not aware Apple was still marketing Apple Watch Series 7 which was superseded 6 months ago. Did you get old stock from a third party reseller, maybe with a battery which is degraded by being left uncharged for 6 months?