Watch Series 4 battery suddenly draining much faster despite same usage pattern

I purchased the Series 4 Apple Watch back in October around time of release, along with the new iPhone Xs model.

With my usage patterns over the last 7 months, on average, I would need to charge the Watch every 2 days -- sometimes getting very close to or needing power reserve by evening on the 2nd day if I did longer workouts on both days and was putting in longer hours at work (i.e. fewer hours asleep/inactive). I usually check the battery at bedtime each night and if I'm ~57% or higher, I know I can get a 2nd day out of the current charge.

In the last two weeks, I've noticed my Watch is consistently tearing through battery power at a consistent, alarming and befuddling rate whereby at late evening (~8-9pm) I'm at 40-45% and at bedtime (usually 11pm-12am) I'm nearer to 35% and must charge within the same 24hrs. I've had little to no change in my average activity or usage patterns. I've installed no new Apps to either my phone nor the watch that could explain this.

Looking back, the only thing temporally that has changed was the 5.2 and 5.2.1 updates to the Watch and/or the recent iOS update, because I first started noticing this issue in the last 2 weeks (possibly 3 weeks, but chalked up one week to above average use). Strangely, I've also noticed my iPhone Xs battery has been draining faster as well. I charge that every night, but usually am at 30% at bedtime while during this 2-3 week interval have been in 10-20% territory and with heavier use require adjunct charging in the evening. I find all of this to be anomalous and not consistent with normal battery capacity depreciation considering how quickly and dramatically it has happened.

I have tried some basic troubleshooting before coming here -- including controlled reboots of both devices (via iOS/watchOS) and soft resets (holding crown+side button on watch or vol up+vol down+side button) on both devices. I've additionally un-paired then re-paired my watch to my phone with no success. I have not yet done a full reset because I find it pretty labor intensive/extreme for something that seems too coincidental in timing to a recent software update.

Anyone else experiencing similar issues? I am open to feedback and troubleshooting steps for those that have solved the issue. Thanks!