MacRumors published a story that Apple has released the third betas of iOS and iPadOS 15.1 to registered developers.

Apple Seeds Third Betas of iOS and iPadOS 15.1 to Developers

Apple today seeded the third betas of upcoming iOS 15.1 and iPadOS 15.1 betas to developers for testing purposes, one week after seeding the second betas and two weeks after releasing iOS 15 and iPadOS 15 to the public.

iOS and iPadOS 15.1 can be downloaded through the Apple Developer Center or over the air after the proper profile has been installed on an iPhone or iPad.

  Apple Seeds Third Betas of iOS and iPadOS 15.1 to Developers