MacRumors published a story that Apple has released iOS 15.3 and iPadOS 15.3 release candidates for testing.
Apple Seeds iOS 15.3 and iPadOS 15.3 Release Candidates to Developers
Apple today seeded the release candidate versions of upcoming iOS 15.3 and iPadOS 15.3 updates to developers for testing purposes, with the new software coming one week after the launch of the second betas and over a month after the launch of iOS 15.2 and iPadOS 15.2. iOS and iPadOS 15.3 can be downloaded through the Apple Developer Center or over the air after the proper profile has been installed on an iPhone or an iPad. There's no word yet on what's included in the iOS 15.3 and iPadOS 15.3 betas, suggesting that it likely focuses on under-the-hood improvements and bug fixes.
