Anecdotally I’m seeing the same thing. Typically I wear my watch to bed for sleep tracking and get a recharge warning about 9-10pm (depending on how much I exercise that day). I’ve had the warning as early as 1pm after the update and I’m regularly seeing warnings in the early evening. I’m also on a Series 8 watch.
Apple is aware and help is on the way.
While you wait, if you prefer to get back to normal recharge cycle now, disable BlueTooth and relay on WiFi for notifications, rely on your iPhone for any missing functions and manually login to your Mac.
Just anecdotally, I have also noticed slightly more battery drain on my Ultra. Some of that is from reduced battery health - I’m now at 96% I believe - but I’ve also heard that removing the weather complication from the watch face(s) that you use can reduce battery drain. There is an obvious issue with the weather complication for some people - they get no data at all, and Apple suggests a solution that for some only works for a short time, so I wouldn’t be surprised if it is also causing some unexpected battery drain.
I switched my weather complications for now from the stock weather app to Carrot Weather and I am noticing slightly better battery performance since switching.
If you are going to try this, I would also suggest removing weather from the Smart Stack of widgets. Scroll up with the crown, or swipe up from the bottom, and long-press to enter edit mode, and then click the “-” on the top-left of the weather widget to remove it.
[edited to clarify that my battery drain has been slight rather than dramatic.]
My Series 4 still holds a day…just about. I’ll probably upgrade to the latest over Christmas, the Ultra appeals but I couldn’t justify the price for my use.
For me the weather, I use Snowflake for my complication, is key. I love having it on my wrist.