https://www.pixiv.net/artworks/94539036
https://www.pixiv.net/artworks/96652775
https://www.pixiv.net/artworks/103414099
https://www.pixiv.net/users/31392159
https://twitter.com/doeeeeeem
https://skeb.jp/@doeeeeeem

just out of curiosity about whether png is better than those so-called tools which can resize, optimize and compress your images 50-80% without any quality loss

Only the image at p.3 encountered the size problem, which is about 24 MB in .jpg format, and it was converted to png for lossless quality instead of compressing .jpg to a smaller size without any loss of quality

Jpg to png is not lossless because jpg decoding standards allows for tolerable error.
You will lose the chance to get better quality with better jpg decoders.
Also you will get the loss of yuv to rgb, if ths colorspace is yuv.
The right way is to use jpegtran(libjpeg or libjpeg-turbo or mozjpeg) to optimize image.

Base +19, Coledas Ukgent +14

fwiw...
Many of the images in this gallery appear to be 'nearly' binary or screentoned and can be greatly reduced in size by simply reducing the bit depth and saving as png.

Base +12, Coledas Ukgent +14