Apple Watch battery draining fast all of a sudden

Did you already try to force restart your watch after the latest update?

Press and hold the side button and the Digital Crown at the same time for at least ten seconds, until the Apple logo comes back again.

Unpairing and connecting it again helped other users:

Unpair and erase your Apple Watch - Apple Support

Did the unpair and repair help? I’m seeing 80% battery use in a normal day no workouts. Ultra. Since 10.5 update

I have done the unpair and repair and my battery life is terrible. No workouts and draining by the end of the day. If I do a workout, it won't make it to the end of the day. I was advised to update the phone to iOS 17.5 but that hasn't helped. I believe there may be an issue with the actual watch, but I'll give it a few more days.

You're welcome 🙂