I also have same issue: instagram & facebook linked.
FIXED! I emailed Shopify and asked them about it, it is a Facebook issue and not them. They gave me the contact details, but before they did I contacted Facebook support and they told me to hit the re-review button so that they can take a look at your store. Apparently there is something that is being picked up that shouldn’t be picked up whether it be just a word.
My store is now published and working and only rejects products that don’t meet the standard which is ok because it has published nearly 1000 of my products!
Good luck everyone just keep hassling Facebook