Gifski presents a very clean, out-of-the-way, and easy to use interface for generating high quality gifs with parameter tweaks.I've been using it for a long time but recently noticed an issue. There is a sort of color artifact applied to gifs, of varying severity depending on the video input. One example, is that the background color of one of my video files is rgb(14, 16, 21) but is transformed to rgb(14, 17, 22) in the gif output.This is a small shift but it is going to be noticable where you are trying to match the background of some other context so as to make a gif's background appear transparent.
The GIF format is ancient and usually limited to 256 colors, but GIfski is able to squeeze out thousands of colors. However, RGB has a lot more than thousands of colors, so Gifski is not able to perfectly match the video input. This is a limitation of the GIF format, not Gifski. Note that Gifski does support MP4 and ProRes with an alpha channel (transparency), which may be a better way of matching a certain background.