The call to curl is missing a closing " pair. Besides, it seems some people submit a low-res image at the post, then post another link as the first reply, which is the case today:

https://preview.redd.it/b2ihaxu2i5261.jpg?width=640&crop=sma...

Care to adjust the jq a bit to look for both, then maybe somehow compare the resolution of the two and download the better one?