PNG files attached to text chat messages are changed by Discord

When attaching a PNG image with extra binary info after its IEND segment (useable as sort of metadata in various cases; one particular case is character, costume or scene data for a series of games by Illusion Soft) Discord removes the extra data and it incorrectly looks as if the user attached a smaller file, breaking the file's intended purpose.

It is ok to optimize images when showing them as previews or thumbnails or similar, but when users decide to download the original, it should be unchanged and with all metadata intact, as there are use-cases where it is necessary.