Apple released iOS 15.0.1 and iPad OS 15.0.1 to the public on Friday night.
The focus this time is exclusively on bug and security fixes, among other things fixed the incorrect calculations regarding the amount of available storage space.
In addition, a problem is fixed that made it impossible to unlock the iPhone 13 using the Apple Watch.
To install the update, open the app Settings and go to General -> Software Update. Then just follow the instructions until the installation is complete.