Adobe Animate- Halloween Workshop W.I.P

I made this gif using Adobe Animate. I looked at animating multiple objects that would be moving at the same time, as well as experimenting with putting different moving objects in the foreground and background. I'm not sure where I went wrong, but when exporting my flash file to a gif, the background of my gf becomes extremely pixelated. The original Photoshop file looked like this:

But I can't figure out where I've gone wrong. Any advice would be appreciated.