HDR should not be "typical web" anything. It's insane that websites are allowed to override my system brightness setting through HDR media. There's so much stuff out there that literally hurts my eyes if I've set my brightness such that pure white (SDR FFFFFF) is a comfortable light level.

I want JXL in web browsers, but without HDR support.

There's nothing stopping browsers from tone mapping[1] those HDR images using your tone mapping preference.

[1]: https://en.wikipedia.org/wiki/Tone_mapping