Along with Wednesday’s security updates, Apple also released a watchOS update for the Apple Watch Series 3. This is intended to fix a bug that could lead to spontaneous restarts of the clock.
WatchOS 8.7.1 fixes reboot issue
The Apple Watch Series 3 was released in September 2017 and is currently still being offered by Apple. The group is therefore still providing updates for this. It was the first Apple Watch that the company equipped with an LTE function using an eSIM.
The Apple Watch update is part of the security patch. This must be installed beforehand so that the clock can then benefit from the fix.