Another theory that some viewers have come up with is that the news anchor underwent plastic surgery. Others theorize that David got a rhinoplasty done, altering the shape of his nose.

Again, David is not one to share much about his personal life on the internet, so if he did have any professional work done, he has not disclosed that information to the public. That being said, if he had undergone a rhinoplasty surgery, that would explain a lot of why people are concerned about his appearance, as bruising is a common side effect of such surgeries.

Source: https://www.distractify.com/p/did-david-muir-have-an-accident