Many iOS & macOS user faced an annoying issue where their device got freeze & even restarted when tapped on this link “
https://t.co/Ln93XN51Kq” in a iMessage app.
The bug was discovered by the famous hacker Abraham Mashri where senders and receivers iOS & macOS device slowed down when sent or received that malicious link.
However the issue has been fixed with an iOS update that Apple made available to developers and public testers today.
The iOS 11.2.5 beta 6 do not have such issues now and for mac, the macOS 10.13.3 beta should fix the problem very soon. So in case if you receive such malicious link on your Mac, do not click or open it or your machine may not respond as you would expect.