He actually is! I double-checked from an inactive 2nd account and the fan tagged him, scaled the text down really small and then hid it behind the main caption (as seen in the screenshot). It’s really sad but this isn’t the first time a fan has done this (I recall another fan doing the exact same trick when Joel bizarrely reposted her daughters school report) - clearly Carrie’s fans have cottoned on that if they tag Joel, they’re pretty much guaranteed a repost. Instagram doesn’t let you directly share a story unless you were tagged in it so the fans are tagging Joel but trying to hide it.
Edit: apologies, in my haste I originally uploaded the uncensored copy of the screenshot. My mistake!