According to caniuse it seems to have been only ever available in nightly.
For anyone interested here is a test site for jpeg xl (and other image formats).
Addendum: Yes we know that you think ml/hexbear/grad are tankies and or .world are a bunch of liberals but it gets old quickly. Try and come up with new material.
Is that a recent change? I remember having it working on Firefox, but I don't think I've ever had nightly installed.
According to caniuse it seems to have been only ever available in nightly.
For anyone interested here is a test site for jpeg xl (and other image formats).
I guess my memory is playing tricks on me then, my bad. Must have been using nightly at some point then