Hey, I'm the developer for nvui. I definitely messed up a bit putting the GIFs in the repo, I noticed it when the actions' build size increased by about 40MB (the display assets get removed now in the build). I don't know if there's a way to remove them now without removing a lot of the git history.
Also about the dithering, I'm aware that the GIFs look horrible, but that was not how they looked when I recorded them, I don't know if it was Github's compression but they look a lot worse when uploaded.