For a theory whose empirical strength is so great that it cannot be doubted, universal common descent certainly is doubted a lot.
Sixty years ago, philosopher of science Thomas Kuhn listed what he described as the “symptoms” of a research field undergoing destabilizing change.
Universal functional requirements, but without the identity of material components — sounds like design.
The prediction Paul Nelson discusses here is that there would turn out to be a single universal genetic code.
Sooner or later, onlookers will realize that UCD is actually bankrupt. UCD doesn’t pay its bills, because it can’t.