You should never transcode lossy source files because there is generation loss in quality.

There is still a lot of reason for Apple to switch from HEIC to JXL for photos going forward since HEIC is patent encumbered so it will never see widespread use.

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dimatura 5 hours ago | parent [-]

Well, JpegXL does have one really cool feature: you can transcode jpeg to jpegxl (and back) losslessly. For jpeg to jpegxl it'll save something like 15-20% in size.

	▲	Gigachad 3 hours ago \| parent [-]
		This is probably going to be a key feature for web platforms. They can convert their massive backlogs to jxl for free space savings.