When did you do the update? It’s quite common and normal for the watch to suck down the battery at a rate alarmingly above typical in the day or two after an update — the watch does all sorts of processing in the background after an update, which requires CPU cycles, which require energy.
(Personally, I wish that it would pause that sort of thing until on the charger … but it doesn’t.)
I’d also suggest not just restarting both watch and phone, but, before restarting, open the app switcher (on the watch, double-click the crown; on the phone, swipe up from the bottom edge) and close out of all apps. If that doesn’t work, I’d suggest seeing if a different watch face fixes it; if so, delete and re-add the offending one.
Also, make sure you’re using the preferred method to restart. On the watch, hold both the crown and side button not just until the screen goes blank, but until after the Apple logo appears. On the phone, press and release the up volume; press and release the down volume; press and hold the power button, again until the Apple logo appears.
If even that doesn’t work … come back here and / or reach out to Apple … there’s lots more to try, but it gets more annoying (unpair / re-pair, etc.).
… but, mostly, just give it a day or three.
b&
