Previously, thumbnails that use gifs have to be hovered over to animate. Recently, however, it's the other way around, with gifs playing by themselves. Hovering over them now shows them as a still image.
This is annoying to me because some gifs end up being too flashy and hurting my eyes, an example of which being SCARLET SHIFT by sirmilkman. It includes flashing lights, including a "title screen" that shows up for a single frame and the blue frame surrounding the image turning red when the player dashes. This could even be dangerous to an extent; what if a epileptic person's got a seizure from one of those gifs?
And in case you're wondering, disabling animated gifs in the settings does nothing to the thumbnails. Not only should this setting affect thumbnails, but turn off auto-playing as well.
UPDATE: They had changed it back to normal, hooray!
UPDATE 2: Scratch that, it seems to only affect the first 10 games on the page. When logged out and on... certain tags, some of them are STILL animated! I also realize that every 3rd game in a row with an animated thumbnail auto-plays it, although I think that's a bug.