Figured out a workaround.
This was just happening to me using the Google Search app. I used to be able to long press > download and it would save to photos.
From the Google app I clicked the 3 dots and selected “share” then chose “open in chrome.” Once in Chrome, I long pressed on the gif and chose download and it saved to my phone. (You may need to give Chrome “add only” permissions for photos in settings but it should prompt you)