Just wanted to say I experience exactly the same. Battery now draining 10% or more every hour - even with all the battery saving tips I've found implemented! Even went so far as to disable wifi, nfc and permanently set screen to 1/4 brightness.
For me it all started Sunday 24 October.
I've had it for weeks before that, and would get about one week out of it before. I just gave it a short charge each morning, while getting ready (prob. 10 min.).
Also note that I slept with it on and had blood oxygen monitoring and all other health features turned on. The only battery saving features back then were no AOD and a dark theme.
Contrast that to now, where I must do a full charge twice daily - even with so many battery saving tips and features that it is no longer an enjoyable experience to use the watch! This is simply an insane decrease in performance!