Apple、デベロッパー向けに iOS 15.3 beta 2 (19D5040e)、iPadOS 15.3 beta 2 (19D5040e)、watchOS 8.4 beta 2 (19S5539e)、tvOS 15.3 beta 2 (19K5541d) を配布開始
https://developer.apple.com/news/releases/