

JPEG does not support lossless compression. There was an extension to the standard in 1993 but most de/encoders don’t implement that and it never took off. With JPEG XL you get more bang for your buck and the same visual quality will get you a smaller file. There would be no more need for thumbnails because of improved progressive decoding.
Best thing is, they introduced some settings to turn that auto-conversion off and they don’t work 🤣 can’t make that stuff up.