Facebook had been working on a GIF button in the comments section for some time now. Couple of days ago the company rolled out a new GIF Button which can be seen in the comments section of a post.
The GIF button lets users search GIF from GIPHY and Tenor for posting in the comments section. The GIF button was added two years ago but users had to enter the URL in the comments section.

Now the addition of the GIF button makes the process easier on mobile. It is currently available only for comments and we hope Facebook is working on bringing it to the News Feeds posts very soon.
The GIF button was introduced by the company couple of days ago and is currently available for users on iOS and Android. The GIF button could soon be made available for Windows 10 users as the Windows 10 Facebook app is an iOS port.
We will be updating this article once we have more info on the time frame the company takes to make the GIF button available for Windows 10 users.