Allow people to pause GIFs natively

Some users have trouble with moving images. The "reduced motion" browser/operating system setting is meant to turn off animations. Currently, I have reduced motion turned on, and I still see animations.

This issue is specifically for GIFs in posts. The extension "Toggle Animated GIF" on Firefox is able to stop them, as a solution for now, but there's no way to see that an image is actually a GIF, and there's no way to click or hover to play it.

I use Xkit Rewritten to solve this issue on Tumblr, in case that's helpful for inspiration. The setting is AccessKit -> Pause gifs until they're hovered over.