Apple has launched watchOS 8.4 which comes with security updates as well as fixes for the bug which prevented certain Watch Series models from charging.
Updates are available on Watch Series 3 and later models. You can download it via Apple Watch. You can download it through Apple Watch app on the iPhone through the General > Software Update menu.
Note your Apple Watch needs to have at least 50% of battery in order to run the update and it must be placed on a charging station and be within the range of the iPhone’s connection.
In addition to the release of watchOS 8.4, Apple also released the first beta version of watchOS 8.5. You can read the release information here.