odd antartica like shape (satdump)

I recently got some APT satellites images from NOAA satellites (18,19) but when i process the audio satdump generates some images with this odd "antartica like" shape that prevents me from using false colors. This specifically appens when I'm reciving daylight images. (only in the processed ones)

do anybody have the same problem and know how to fix this?

this is an exapmle but it appens in every photo in the same exact way.