Adobe added JXL as a compression option for the DNG format last year. Previous options were JPEG, Lossless JPEG, Deflate, and nothing. Apple used Lossless JPEG. Apple engineers have decided to take advantage of the option Adobe added last year to make their DNG files smaller.

You wouldn't want 24MB files with GPS and face detection metadata served raw on the Web anyway.

Serving images from CDNs is not the only use case for browser JXL support. Browsers can perform client side processing of images before upload. They even host fully featured image editors like https://photopea.com. And sometimes you do want to see an original image from your camera in your browser, like say on the web version of Google Photos.

I wouldn't want them on my phone either, but maybe that's just me.

Of course it’s .dng; .jxl doesn’t carry the metadata needed to process a RAW image because it’s not intended for that.

Which metadata exactly? Is the actual concern that someone unaware might accidentally stumble on the unprocessed image?

To start with, without a linearization table, white and black levels, how exactly do you expect sensor data to be usefully interpreted?

Well, I assumed Exif and embedded color profile would have been expressive enough for this. I do agree I'm a bit out of my depth when it comes to raw photo data but Exif seemed to have properties for everything, even counting the kitchen sinks in the image.

Where did that come from? It feels like you’re working backwards from some bad feelings felt about Apple.

Hmmm, is the jpeg xl data inside the dng not demosaicized?