Well, of course we don't know of a specific miracle drug they've denied us, because it isn't until after a drug is in wide use that you find out whether it's a miracle drug or not. But we can see that there were enormous numbers of miracle drugs in the 20 years immediately preceding the safety regulations, and almost none in the 63 years since then. There have definitely been some† but a very large slowdown is clearly evident if you look at the history. Most of even the important new drugs since then are slight variations on previously known molecules.
A reasonable inference from these observations is that safety regulations have denied us a lot of miracle drugs.
______
† zidovudine, Paxlovid, oral rehydration therapy, ivermectin, propofol, SSRIs, sildenafil, acyclovir, misoprostol, ritonavir, and arguably buprenorphine come to mind; and time will tell whether lovastatin and semaglutide belong on this list or on the failures list with fen/phen and heroin.