Ecosystem being slow to adopt it is something that can be fixed or improved, but also more importantly (given jpegxl & avif comparisons) are things that will impact any new image format.

Meanwhile annoyances of the codec tend to be things that are dramatically harder to deal with. Like HEIC being a license minefield and also slow as shit. Or that many of these newer image codecs do not have ways to work with them in a memory efficient manner like jpeg does (see eg libjpeg-turbo's sample size & skip scanline options). Or WebP insisted on being in a RIFF container for... uh... absolutely no fucking reason whatsoever afaict. Fortunately RIFF is so trivial that this overhead doesn't actually matter in practice, but then HEIC & AVIF dials up the annoying container bullshit to 11 thanks to their video heritage with ISOBMFF