It's also relatively easy for new formats to be adopted - the html picture tag makes it really easy to serve the same image in multiple formats to allow for backward compatibility.
And of course image decoders are easily distributed - JXL's encoder/decoder are open source.
The combination of those two factors probably means that this will never be a settled area now. It's fairly easy for websites to adopt a new format and there are strong reasons to. Means, motive and opportunity.
I reckon Chrome will cave in eventually. The pressure on browser performance is intense. Unless they want to see Safari faster in benchmarks of image heavy pages they will have to adopt it.