Well, that could be a trend that has been making inroads into one's chatting habits. However, let me make it clear that I have not observed any such surge in my own WhatsApp contacts or Groups. Not that we do not use GIFs, but there has not been any surge in the frequency.
Videos in the GIF format will save you data and possibly compresses the size of the file ( I am not sure, maybe those who know the details can put in their views in that regard here) and that could be one of the reasons for the widespread use of GIFs. Moreover, WhatsApp videos and images are generally "Forwarded as Received" kind of thing. So I would guess, that can explain the surge in the usage of GIFs.
Live....and Let Live!