If yours got converted, then the server you’re using, doesn’t support drag and drop gifs.
Instead of drag and drop, upload the gif to some other server, that allows such stuff and use that link in the  format as given by @Riccosuave@lemmy.world.
How do you upload gifs in lemmy comments? 😮 mine got converted in a pic
You just use the image link format like this:
If yours got converted, then the server you’re using, doesn’t support drag and drop gifs.
Instead of drag and drop, upload the gif to some other server, that allows such stuff and use that link in the
format as given by @Riccosuave@lemmy.world.