The referral page for Chase Sapphire Reserve “has concluded” according to the dedicated referral page. The Chase Freedom card gets the same message as well.
Chase offers a nice bonus for referring a friend to many of their cards, all of which are still available with the exception of the Sapphire Reserve.
Regarding referral links which have already been generated: when I tried clicking on various referral links, some of them work while most of them give a pop up with a message indicating the offer is “no longer available” and redirects to the current offer. Oddly, the URL of the “redirect” remains the same. I’d guess there’s some other issue going on there, and that existing referrals will work fine (probably even the ones giving the redirect).
Chase declined to comment on whether the bonus will be reinstated. Most likely just a refresh and will come back at some point.