FYI in the new release (which combines the video and image buttons in the composer (and which just rolled out)) you can choose .gifs on your computer.
This ... should be animated
https://morel.us-east.host.bsky.network/xrpc/com.atproto.sync.getBlob?did=did:plc:ragtjsm2j2vknwkz3zp4oxrd&cid=bafkreid3wrvjpot5sjvxtv4uj6jtfwlsgalzignw7s5etmpuyuyoabqqu4