Before the battery drain issues, my morning exercise would take the watch from 100% to 53-58% depending on the day.
With the battery issues, the watch went into reserve power about 2/3 of the way through my exercise and was totally dead by the time I got home, unless I used airplane mode.
As a last resort, I:
Erased all data, kept cell plan.
Set up as new (restoring from backup didn’t change anything.)
Disabled autogenerated playlists on watch.
Synced my main playlist and one set of earbuds.
Both mornings since then I’ve had 68% battery left after exercise, with everything turned on. So, for now, doing the steps above gave a dramatic improvement from what I thought was ”normal” battery life and the excess drain issue is gone.
Both iPhone and Watch are on latest OS.