I downloaded this manga from e-hentai before.I found out that size is larger than oringinal when I bought it on DLsite, but clarity is lower. I saved it as jpg, its size is almost the same as original PDF. Although size of the manga is smaller, it is more close to original file.
Final image (p187) is the tokuten of this manga, its clarity is higher than p184.
Right, that's how it should look like. Note the differences between 2 versions. Whatever the tool was used to render PNG, it did not do it properly. And this is a frequent mistake in galleries, where you see x1919 resolution. Maybe you could describe the process and mistakes, to inform other users.
Fyi you could upload the PDF on any file service or as a torrent.