That was Mozilla's stance. Google was thoroughly hostile towards it. They closed the original issue citing a lack of interest among users, despite the users themselves complaining loudly against it. The only thing I'm not sure about is why they decided to reopen it. They may have decided that they didn't need this much bad PR. Or someone inside may have been annoyed by it just as much as we are.
PS: I'm a bit too sleepy to search for the original discussion. Apologies for not linking it here.
It wasn't just a blatant lie for lack of interest, they also went out their way to benchmark it and somehow present it as inferior to AVIF.
> The only thing I'm not sure about is why they decided to reopen it.
It's almost certainly due to the PDF Association adding JPEG XL as a supported image format to the ISO standard for PDFs; considering Google's 180 on JPEG XL support came just a few days after the PDF Association's announcement.