Just to give an English version of what are presumably being stated above, protip: try to use animated webp instead of gif if you can (better quality, smaller file size, etc)
Basically animation is one of the two things that webp is actually good at (the other being lossless if 8bit-per-channel is fine), otherwise the format is a big pile of "meh" and/or "why bother?"
(Of course, if the originals were already in GIF format, then I'm not sure you can do lossless transcoding to WebP - technically an animated PNG can reduce the file size some in such a case, but not as much as lossy animated WebP not to mention animated PNG has the same file size limits as normal PNG which I believe is 10MB compared to GIF and WebP's 20MB file size limits not to mention resolution limits for animated PNG where you have to stay below 1280 pixels or else the animation gets stripped out for the non-full-size images not to be confused with the thumbnails)