Same here. I have almost no notifications pushed to my watch as I use it mostly to track sleep and get call/text notifications during the day. I had it on do not disturb/sleep after fully charging last night before bed. Was down to 86% when I woke up - which is about twice as fast of a drain. By noon, was down below 60% and still set to DND.
I have it set not to light up for any reason aside from a touch. Brightness is as low as possible (which I often find it is strangely bright and have to go back, switch to brighten, then lower again).
After having this thing well over a year and never having issues, this seems like a terrible change. Using it so little, I've always been able to go 2 nights before charging. Hope this is a bug they fix over a foreshadowing of future performance.