So ...

There are two ways to add GIFs from Gliphy: using the associated plugin (called Giphypress) and inserting the actual image URL grabbed from the Gliphy website.

The plugin-based solution will embed the GIF file as an iframe into your post/page. Basically, an iframe is a web page (or HTML element) embedded inside another page (or HTML element) ... and the truth is that search engines don't like iframes ... In other words, iframes could hurt your SEO ... Also, for obvious security reasons iframes are disabled by default on many hosting environments including WA!

The URL-based method has no limitations ... Basically, you are using a "regular" external link ...

Personally, I recommend you to forget those iframes ... Of course, the choice is yours - always :) -, and if you have websites hosted outside of WA you can use the plugin if you want ...

So let's see each option ...

And let's start with the Giphypress plugin.

Here it is:

https://wordpress.org/plugins/giphypress/

Note: you'll see the usual warning message saying that the plugin hasn’t been tested with the latest major releases of Wordpress ... Ignore it ... I've tested the plugin on Wordpress 5.1 and works fine.

It's a relatively small plugin (830 KB), but let's see the usual speed tests ...

Here are my results before installing the plugin ...

... and the result after installing and activating the plugin:

No more comments needed ...

Now let's see how it works ...