ffmpeg wasm gif output size too big

Question

I'm using "@ffmpeg/ffmpeg" for browsers with React, when I convert videos to GIF I'm getting too big file sizes.

Main problem is in web I cant optimize/compresss gif, so I need some methods to optimize output GIFs in browser.

Input	Output
7.34 MB	29.55 MB
202.59 KB	1.21 MB
3.41 MB	52.04 MB

await ffmpeg.run(
  "-i",
  "video.mp4",
  "-vf",
  `fps=30,scale=640:360:flags=lanczos`,
  "video.gif",
);