Google apparently wanted to be one of the "cool kids" supporting AVIF. When they removed the JPEG XL code from Chrome, they created the excuse that there was little demand for it, along with some other disingenuous talking points that didn't quite make sense. Ironically the project that ended up becoming JPEG XL was started by Google employees in Switzerland.
Anyway, I’m glad Google is supporting JPEG XL now. I wanted to use JPEG XL files for a project I started a month ago, but it was a non-starter with global usage under 20% at the time.