Ultra 2 + WatchOS 10.2 -> DESTROYED battery life

I have an ultra 2 that's only a few months old (obviously.) With previous WatchOS versions, the battery life on this was amazing. I'd let it charge to 80-85% in the evenings, put it on my wrist before going to sleep, and wake up at over 75%. By the end of a full day, when I put it back on the charger, it would be at 50-60%.

I've done each WatchOS upgrade since I purchased it, and while the battery life the next day would be slightly less, it would go back to "great" within 24 hours.

Since "upgrading" to WatchOS 10.2, however, the battery on this "ultra 2" is worse than my wife's 4 year old Apple Watch 6. Now I put it on at night with 80% and I wake up to 65%. I charge it back to 80% around 9am, and by 3pm it's down to 50% again. I haven't changed ANYTHING about how I use the watch. I have the same face. Same always-on display. Same apps, same (lack of) exercise. Everything is the same except that I'm on WatchOS 10.2 now.

This is an Ultra 2. This thing is supposed to have 2 days of battery life, not 12 hours! In the settings, the max battery capacity is still at 100%, but at the rate 10.2 is draining it, the max capacity will be dropping fast, I'm sure.

I've tried rebooting the watch. I've tried rebooting my iPhone. I've tried unpairing (resetting) and re-pairing the watch. Nothing seems to fix this.

Is there anything I can do to get back the battery life I paid a LOT of money for? Do I have to take this to an Apple store so they can give me a run-around?