I'm giving #LibreWolf a spin. There's a number of things I'm not particularly satisfied with, including the inability to straightforwardly import/copy over a profile from #Firefox, and the choice to default-enable some pretty aggressive privacy feature that break actually useful functionality (such as browser fingerprinting protection that disables dark mode support). OTOH, I was looking forward at its #JPEGXL support.

1/2

This is something that #Firefox actually ships in its #nightly builds, and #LibreWolf enables in its standard builds, which is nice … except for the fact that the #JPEGXL support in Firefox is actually … pretty poor 8-(
The basics are there, but transparency and animations aren't properly supported (go to https://jpegxl.info/test-page/ after setting image.jxl.enabled to true in about:config). I reported the bug upstream. Not sure I can hope to see it fixed anytime soon though.

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JPEG XL Test Page

It's a bit of a pity that the only open source browser with proper JPEG XL‌ support currently seems to be #OtterBrowser https://otter-browser.org/
Otter Browser

Otter Browser aims to recreate the best aspects of the classic Opera (12.x) UI using Qt5.

@oblomov I changed image.jxl.enabled to true, also restarted Firefox, but still can't see the jxl images on the test page. How come? (Firefox 127.0.2 on macOS Sonoma 14.5)
@waltertross AFAIK the only version of Firefox that has JPEG XL compiled in is Nightly. The others have the config option, but the toggle does nothing because it's just not compiled in.