Lower image quality for new image uploads? (dithering/artifacts)
New images uploaded to the site seem to be undergoing some kind of preprocessing workflow that older images did not, because they are being heavily dithered and winding up with banding and coloring artifacts, especially visible on gradients. This might be affecting PNGs only, after looking at multiple examples.
Quick way to zoom in without other tools: https://pixelied.com/features/image-zoomer
It looks like the above image has been saved as a gif (so, color quantized), low color count webp, or someone has opted to use TinyPNG and lossily drop colors, and then still serve the file as a png. It's very confusing, either way, this image quality is much lower than it should be. If this is in efforts to save space then I understand, however that would make re-serving the asset as a png make no sense after a middle step, where it would just make sense to save as a q98 jpeg and transfer the metadata if you're going to go lossy anyway, the image quality would be much higher overall that way.
If you go back to older images on the site, they do not have this problem: https://civitai.com/images/150224
So this seems to have been silently updated in the background, now newer images you can still get original+metadata, but preexisting previews still have the dithering effect. Confusing.