Since iOS 14 image_picker hasn't worked for Gifs chosen on iOS when the user selects the new photo permission "Selected Photos". You can change the access to "All Photos" and Gif's will be animated, change it back to "Selected Photos" and select the same Gif and it won't be animated.

 final _picker = ImagePicker();
    try {
      final pickedFile = await _picker.getImage(
        source: ImageSource.gallery,
        maxWidth: 400,
        maxHeight: 400,
      );
 final result = await pickedFile.readAsBytes();