Apple has started rolling out iOS 15.3 and iPadOS 15.3 to multiple devices. The two OS updates contain fixes for at least ten security issues but lack any new features or changes. iOS 15.3 and iPadOS 15.3 are large updates too, considering their contents.
https://www.notebookcheck.net/Apple-releases-new-iOS-and-iPadOS-updates-to-address-ten-security-issues.596038.0.html