Charge Limit not working - Apple Watch 8 with WatchOS 11.1

The 80% charge limit has stopped working on my Apple Watch 8, after updating to WatchOS 11.1

As far back as I can remember, the Watch would always stop charging at around 80%, with the occasional 100% top-up every couple of weeks.

Now, since updating to OS 11.1, it has been charging to 100% every single time.

I have not changed my routine in any way, or gone on any recent trips.

I always charge both my Watch and iPhone the moment the 5:00am alarm goes off, and take them both off the charger at around 6:00am.

Normally both devices would be at 80%. Now only my iPhone stops at 80%, while the Watch goes all the way to 100%.

Does anyone have any ideas how to resolve this issue?