I think there is a wider issue happening because my Watch SE (which is under 1 year old) has been draining way faster than usual since the latest software update. This has actually happened to me a few times with software updates in the past year with Apple so I now try to turn off automatic updates.
Example - today I've worn my watch for 6 hours. Used it to track 1 x hour workout and 1 x 45 min workout. It went down to 28% in that time!
Query with Apple Support if it's happening after phone and watch software update because I am sure its normally a bug in their software.