Apple Watch Series 10 battery drains quickly after update
Apple Watch Series 10 OS version 26.6 - battery suddenly drains quite quickly since last update.
Question marked as
Did you already try to force restart your Apple Watch after the latest update?
To force restart your watch, press and hold the Digital Crown and the Side button together for about 10sec, until the Apple logo comes back again.
If this does not help, unpairing and pairing the Apple Watch again has helped other users.
Unpair and erase your Apple Watch - Apple Support
Also have a look at the posts in this discussion:
Apple Watch battery draining fast - Apple Community
There are also some background processes still going on for a certain time after the update, resulting in more battery usage.