gif files not animating

If the image is truly an animated GIF, then you select it and press the spacebar. Quick Look will open the GIF and display the animation. Otherwise, the animation will be shown when you open that GIF in your choice of a web browser. Neither Preview nor Finder will show animation.

In what Apps?

I have attached several animated GIFs to Apple Mail in macOS 11.6.2 and macOS 12.1 in the last few minutes, and the animations play normally. Most of my animated PNG also play as Apple Mail attachments.