ezgif uses a lossy GIF compressor written by me — author of gif.ski.

I can run:

     gifski -Q50 jazz-chromecast-ultra.gif -o even-smaller.gif

and it reduces the same file by 65%. With -Q20 it can be 78% smaller: https://gif.ski/jazz-ultra-small.gif

By that measure, gif.ski is 78% better than itself!

With lossy compression it's always possible to make files smaller, and smaller, and smaller. Comparisons of lossy encoders without controlling for quality lead to such absurd results. See https://kornel.ski/en/faircomparison