this gif image increase file size almost 3 times after processing

[Calx-Takeno]

this is original image url, original size is 7.16MB https://imgs.takeno.app/0x0/upload/2019/11/01/42349584306327.gif

after processing,size is 20.2MB just quality is 50% https://imgs.takeno.app/0x0,q50/upload/2019/11/01/42349584306327.gif

On my opinion, file size should decrease as other image format. Please advise.