Me too! Quite a significant one. It's really weird. I have a Watch4 too and swap between the 2 so I'm never without, and I have just this minute got the update for that. It'll be interesting to see if there's a difference there.
Hilariously, my Watch4 appears to be going down the drainage route judging by tonight's performance!😆 I'll do a side by side settings check tomorrow and maybe it will catch up
I have the watch 5 pro LTE. Before the update. I could get 3 days 9 hours after a full charge. After the latest One UI 5 update, I had even cleared the cache, I now get 2 days 3 hours.