For the record I've barely touched the watch today - far less than I would typically use it. I deliberately avoided using it to see how rapidly it would use the battery at what is essentially "idle" use.
I think it's clear at this point that this is a bug and it's only impacting some people.
Edit: In case it isn't obvious from the graphs I posted, in the first graph I still have 41% battery left, so I could have probably worn it for a full 24 hours continually if I'd wanted to, compared to just 8 hours on watchOS 10. So it's only getting about 1/3rd the battery life of watchOS 9.6! Something is clearly bugged on mine.