I had a match where I went for the rez, started the animation and got canceled because someone else in my team died and the respawn timer got reduced for the ressurected target.
When something similar happens (the person getting ressurected disconects or 2 Mercys try to ressurect the same person) ressurrect gets refunded not canceled.
(The fact that ressurect is basically nerfed thanks to this change is another topic)
Seems like a bug but since rez is such an unfun ability to play against, I’m ok with it