Question about continuing large illustration graphic submissions

[fugauploader]

The page of Fuga: Melodies of Steel has incomplete illustration graphics mainly uploaded by TommoTheCabbit, each downsized to 1440x810 while the original images are 1920x1080, with a couple of even bigger ones at 3840x2160. How should I go about continuing these submissions? Original size or downsized, and what should I consider about file size?

[Barack Obama]

https://www.spriters-resource.com/ninten...iesofsteel

An illustration needs to be native size.
When the uploader edited them in a graphics program to make them to smaller, you can replace them.