So i found one cool male gif head but for some reasons the file is broken (Transparency or idk) and i tryed everything but i can't fix it, so im now trying to do the head by myself from the beginning. I came to half way and now i have problem copy-pasting colors from original to new file. When i copy the color and try to color the eyes on new file it doesn't allow me, it changes to some other like white or pure purple. Can someone pls explain me this?
https://imgur.com/a/PggNdjn
And i've noticed this odd break lines on original image.  

What software are you using/has this happened on multiple platforms  

Im using gimp rn  

Sounds like the head is indexed? Check the file settings i dont use GIMP but try to see if you can change it from being indexed.
[Edit]
Try this:
https://docs.gimp.org/2.10/en/gimp-t...ange-mode.html  

Yeah try and turn the indexing off.