MacRumors published a story that Apple has released the first betas of iOS 14.3 and iPadOS 14.3 to registered developers.

Apple Seeds First Betas of iOS 14.3 and iPadOS 14.3 to Developers

Apple today seeded the first betas of upcoming iOS 14.3 and iPadOS 14.3 updates to developers for testing purposes, one week after releasing iOS 14.2. iOS and iPadOS 14.3 can be downloaded through the Apple Developer Center or over the air after the proper developer profile has been installed. There's no word yet on what's included in the iOS 14.3 update, but it likely focuses on features, bug fixes, and performance improvements that weren't able to be included in the iOS 14.2 release.

Apple Seeds First Betas of iOS 14.3 and iPadOS 14.3 to Developers