Apple says that an issue with watchOS 1001 that caused some Apple Watch batteries to drain excessively quickly, is to be fixed in an update that is coming soon.
Some Apple Watch users have seen excessive battery drain since watchOS 10.1
It's normal for any device to see unusually quick battery drain after an update, as it works in the background on tasks such as building an index of data. That usually lasts only a couple of days, but an unknown number of Apple Watch users have been seeing a much greater battery drain, which has not improved.
The drain is far from universal, but sufficient numbers of users have experienced it that Apple has now informed Apple Authorized Service Providers that it is working on the issue. As first spotted by MacRumors, the providers were informed via memo which acknowledges the issue and reports the fix is coming, but without any further detail.
Consequently, it's not clear how many users have been affected, or whether the battery drain is associated with all models of Apple Watch. Anecdotal evidence suggests that it's been spotted on all current models, plus older ones going back to Apple Watch Series 5.
The watchOS 10.1 update that has caused the issue is compatible with Watches back to Apple Watch Series 4.
This is not the first time that Apple has had to make a similar update to fix a battery drain on the Apple Watch. In 2020, Apple put out watchOS 7 around a month after the original watchOS 7, for the same reason.