Something must have happened with the beta 2 of iOS 15 that Apple released a few days ago for the developer community because the company launched a New to build of this same beta without changing version. All developers can update comfortably as if it were a stable version.
This “beta 2a” is a revision that fix the bugs of the original beta 2, so that we do not find any novelty or surprise. Normally, Apple issues this type of notification when an error causes too many crashes or poses a risk to the device or the data we store on it.
Public betas are coming, but they are not more reliable for it
Along with this update, Apple released first public betas of iOS 15, iPadOS 15, tvOS 15, watchOS 8 and macOS 12 Monterey
But precisely because of this type of update, we recommend that you don’t install these betas unless you know what you’re doing. We also do not recommend that you use them on your everyday devices, as you can put your data at risk and deteriorate its performance.