Hello MadPropz101, as you may know, gifs aren't great at handling transparency, Alpha threshold and Alpha dither advanced settings in Spine 3.7 should help you find a better balance, you could also export a PSD, then use Photoshop's exporter to control settings better.
I tested APNG format and a transparent video in PPT, but both seem to be unsupported by it, otherwise I totally would have recommended either of them since the quality would have been higher.