This update adds ProRAW for iPhone 12 Pro and a handful of other features and fixes.

Apple’s big product release roadmap for the fall continues apace, with new iPhones, iPads, Macs with Apple silicon, and macOS Big Sur. But it hasn’t forgotten about iOS 14, which is gearing up for its third big point release.

Apple has now begun beta releases of iOS 14.3. It adds the promised ProRAW format to iPhone 12 Pro and a few other small changes.
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https://www.macworld.com/article/3596437/ios-14-3-apple-releases-first-beta-to-devleopers.html