I’m pretty sure the iMessage previews are generated by the sender and sent with the message itself - the recipient doesn’t parse the link. Can easily be proven

I’m pretty sure the iMessage previews are generated by the sender and sent with the message itself - the recipient doesn’t parse the link. Can easily be proven by sending someone a link that only you can access (hosted on the LAN which the recipient can’t reach) and seeing if the recipient still sees a preview.