Like any new operating system, iOS 15 has had its share of bugs, including an annoying one which prevented users from unlocking their smartphone with their Apple Watch, a very useful feature in these days of masks which renders FaceID useless.
iOS 15.0.1 includes 3 specific fixes, the first being the fix for the Apple Watch unlock problem.
It also fixes a much less significant issue – the unexpected start of workouts in audio meditation on Apple Watches for Fitness+ subscribers.
Lastly, it fixes an issue with the Settings app where a full storage alert was erroneously displayed for a number of iPhone users.
If you are having any of these issues, you can update to the latest public release of iOS 15 by checking for updates in Settings.