In addition to iOS 11.2.5 shipping, Apple has released watchOS 4.2.2 for all Apple Watches. The current build is 15S542.
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The new version is available on Apple’s developer center and is rolling out to all users now.
Release notes simply mention ‘improvements and bug fixes’ without noting any specific changes. Anecdotally, testers have reported faster performance when navigating in the redesigned Workouts app on watchOS 4.
Apple Watch users running the latest developer beta version of watchOS 4.2.2 should not need to update.