Note that AVIF is badly broken in Gimp. Save an image as AVIF, then load it again. Decompose the Luma and Chroma. You will see that the chroma is on a perfec

Note that AVIF is badly broken in Gimp. Save an image as AVIF, then load it again. Decompose the Luma and Chroma. You will see that the chroma is on a perfect 2x2 pixel grid, as if it was upscaled using nearest neighbor upscaling. This does not happen for JPEG.