While this gallery has larger filesizes than the newer gallery JPG upload, PNG images will have large filesizes for photo type color images. Another problem is that the blurry text of the photos suggests that upscaling was used. This is because a 1920 pixel photo that was labeled with text will have the text sharp. And even if the image was originally larger, downscaling would keep the text relatively sharp or if the size was small, then JPG aliasing would occur and be visible as sharp jagged edges. However, those aliasing artifacts aren't here but are instead blurry as if the waifu style upscaling was used.
This is not a complaint that expert systems or neural network type upscaling is either bad or that it doesn't always result in a better image. They can improve an image. But the real issue here is THE TRUTH. The gallery is to be as close to what the source is. Editing or upscaling the source before uploading as a gallery means yet another layer of change was done. Can you imagine the chaos if people started editing translations with personally chosen word improvements before they were uploaded?