iOS and iPadOS versions 15.3 were pushed in order to patch a slew of vulnerabilities on iPhones or iPads. However, it left one, which may have allowed the execution of "arbitrary" code. Never fear, though, v15.3.1 is here to address this potential security issue. There are also now new corresponding macOS and watchOS versions available to install.
https://www.notebookcheck.net/Apple-releases-the-incremental-iOS-and-iPadOS-15-3-1-update-to-fix-a-crucial-security-discrepancy.598856.0.html
Fixing security gaps is good but Apple must also stop its half-daily requests to join iCloud and accept its terms! This has been annoying since mid December 2021. If a user rejects them once, he is serious about his decision and does not alter his mind just because of being asked twice per day again.