Same issue here - S4, lasted whole day before (at around 25% at 10pm).
Since sunday (1.10.23) at around lunchtime, my battery is being wasted by the watch.
Monday my battery was at zero around 5pm. Yesterday it lasted from 6.30am to 12pm.
Today I started at 6.30 am at 100% and now (7.11 am) I am at 75% - just sitting, drinking coffee and getting more and more angry about this situation.
I already uninstalled the 3rd party apps on my watch and restarted the watch - nothing helped so far.
I would like to go back to watchOS 9 - or at least have a fix, that gets the watchOS background processes under control!
I won‘t take my watch charging things with me all the time - I need a working watch throughout the day (tracking of sport and health parameters). And if this isn‘t to be fixed, I can‘t help me to get the strange feeling, that this might be intended to push people to buy a new apple watch - which I won‘t do. I think, I then will switch to Garmin…
Btw. while writing this, my watch dropped to 66% (7.20am) - great work, apple!!!