It‘s now been about 4h into the day, and my watch is at 87%.
Before iOS14/watchOS7 GM, it reached this level around 6-7 hours into the day.
I usually end my day at close to 50%, now it‚s 20-30%.
Battery life is definitely worse, but it‘s been the same for previous x.0 versions.
There will most probably be a x.0.1 release soon which should solve these issues.