Apple has released a small update for iOS 15, building on iOS 15.1 that it issued last month. iOS 15.1.1 fixes a specific bug, but only for recent iPhones. iOS 15.1.1 likely arrives a week or two before iOS 15.2 debuts.
https://www.notebookcheck.net/Apple-releases-iOS-15-1-1-to-select-iPhones-globally.580137.0.html