On the 31st of March, as the pinned post in this forum suggests, my watch updated to 5.10. Since then the computation of the body battery has changed significantly:
Any insight into why? The key change seems to be in the over night recovery, which suggests a change in how heart rate variability (HRV) is calculated. To illustrate, here is a day before the update:
Which shows low stress / high recovery over night. Here is a current one (note that my heart rate over night is, for all intents and purposes the same for these two nights):
