https://wccftech.com/ios-15-4-and-ipados-15-4-beta-1-now-available/

Apple has released the first beta of iOS 15.4 and iPadOS 15.4 beta 1 to developers with iPhone and iPad.

It was just yesterday Apple seeded the full and final version of iOS 15.3 and iPadOS 15.3 to the public and the company has already seeded the next software release to developers in the form of iOS 15.4 and iPadOS 15.4 beta 1.