Apple Watch not charging to 100% after latest update

Did you already force restart your watch after the latest update by pressing the Digital Crown and the Side button together for about 10sec, until the Apple logo comes back again?

Also check the settings for Optimised Charging:

About Optimized Battery Charging on Apple Watch - Apple Support

Falce wrote:

apple watch not charging to 100% with latest update

Mine charges to 80% unless I override that with "charge to full now," which is on option presented when I check the battery level. I believe this is by design to preserve the battery life.

Hopefully it is only charging to around 85%, which is better for the battery's health and longevity.

Not letting the battery drop below 25-30% is also good for the battery.

M1 Mac mini, macOS 26.2;  Watch, Series 10 GPS-only, watchOS 26.2; iPhone 16, iOS 26.2; TV 4th Gen, tvOS 26.2 HomePods, audioOS 26.2