I got the same results as Ofnuts. Gif keeps the order but png does not. But then the image only uses 43 of colours and that blue is not one of them.
Tried all sorts of things, came to the conclusion that for a simple edit then use something else.
mtpaint seems to keep the colormap. Your original edited in mtpaint and the edited image open in Gimp.
mtpaint is not something I normally use, running it here from my home partition, all the dependencies are already there from other programs. example: https://i.imgur.com/sleZruS.jpg
edit: one question out of curiosity. Where (which application) did the png come from originally?
Tried all sorts of things, came to the conclusion that for a simple edit then use something else.
mtpaint seems to keep the colormap. Your original edited in mtpaint and the edited image open in Gimp.
mtpaint is not something I normally use, running it here from my home partition, all the dependencies are already there from other programs. example: https://i.imgur.com/sleZruS.jpg
edit: one question out of curiosity. Where (which application) did the png come from originally?