hi, if you have still not found a solution. i may of found it. after trying several things including deleting all my watch faces and apps the battery was still draining, after taking it off the charger i could literally see the battery draining. but after completely disabling Samsung health it seems to have done the trick. literally after 4 hours it as only gone down 5% compared to 70%. i disabled all notifications on the phone app, then also on the phone go to manage items and switch everything off. then on the s health app on the watch. swipe through to settings and turn off all health nudges, the go to workout detection and then again turn them all off.
I'm pretty sure that was the problem.
I'll check back after a day or so to see if it truly worked but for now it's def working.