watchOS 5.3.8 (build 16U680) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2020-07-15T17:28:34Z. The update package is 50.26 MB. This is a delta (partial) update that requires 5.3.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 37b244238fa9e57a69b093050f877ffe872fb53e.zip.