It evolved into Butteraugli which was incorporated into libjxl, which powers the reference JPEG-XL encoder. It also optionally powers libaom's encoding, which i

It evolved into Butteraugli which was incorporated into libjxl, which powers the reference JPEG-XL encoder. It also optionally powers libaom's encoding, which is in turn used by libavif and libwebp2 (for the WIP WebP2 image format).