>in all other lossy sources apng doesn't come close to webp
Obviously if you're using grainy, lossy sources, you're not doing animation. At which point, you may as well be using one of the many dedicated video
formats that soundly defeat WebP in compression ability. The whole idea of WebP stems from a fundamental misunderstanding of the uses for GIF due to years of people taking shitty video clips and turning them into GIFs. Lossy video is not an animation format's strong suit, quite obviously. But for actual animations? Even the highest compression lossless video formats can't beat animation formats that make use of delta-frame compression techniques. Here's a simple example to illustrate my point. This is a lossless animation in animated PNG and x264 video in lossless mode with the highest compression setting possible ('placebo' in ffmpeg). Even one of the highest-compression lossless video formats currently available (x264 handily beats x265, VP8, and VP9 in this area) still can't touch the file size of the dedicated animation format. Even though the dedicated animation format makes use of what is at this point an absolutely ancient lossless compression scheme that's been superceded by newer methods for some time now, the simple fact that it uses delta-frame compression (deleting the visual information that doesn't change from frame to frame) allows it to beat out fancy modern video formats that don't. A similar comparison can be made for many animated GIFs to video formats as well, though obviously APNG produces much smaller file sizes than AGIF.