This started with the watchOS update to 10.0 and it has not been fixed so far (as of 10.2).
I have heard this specifically and seen it mentioned on one of the larger Apple related web/media sites (not an Apple site).
When I first bought my Series8 watch in March I was getting ready almost 48hours of use out of it, now (12/30) I am lucky to get half of that if I don't use too many apps.
I've even gone in and adjusted settings, turned off background updates for apps that I can live with them only updating when I use them.
I've looked at the battery health and Im still at 93%, and looked at the battery drainage by app to see how I might be able to tweak settimhsvor delete battery hogs to no avail.
My personal opinion is that Apple, starting with WatchOS 10 has basically overstuffed and under optimized Sustem Services and the underlying WatchOS.
I Sam Marcos fortunate that using a 20W USB C charging block my watch can fully recharge in an hour or two