Hello,
I started a case and sent my Apple Watch 7 to Apple in an attempt to get the 82% battery replaced.
It returned today with no remarks, but the battery was not fixed.
When I contacted again, they informed me that if the battery on my Apple Watch is still at 80%, it cannot be replaced. It makes no sense for them to open up a watch and fix the battery if it's still "too good," thus it doesn't matter if I'm prepared to pay because they're probably going to replace the entire watch.