How are supermassive black holes able to grow so quickly to reach such an enormous mass in this early epoch of the Universe?
>>> That simpley means that, matter was already there before the Big Bang isn't it?
Maybe you read one of many attempts at an explanation somewhere that used anthopomorphism as a rhethoric device, but the only creative effort in that sense lies with the author.
Unless something changed recetnly, we don't know what has happened in the first moments of the big bang, because "time" stops making sense in these models. The details are beyond me. It seems to imply two things. First, if the model is naively extrapolated in a thought experiment, then back tracking the rapid expansion means you arrive at a singular point, but, as said, we don't get that far mathematically.
Second, arguably then it's still a matter of interpretation of what was "before", and where, or just what!?! As for the creative author, that's not challenging the universe, rather our conceptual space.
Third, the Grand Parent trivially suggests that if an event can't have happened so quickly, then naive extrapolation implies it must have started before the beginning of time. This seems to be a contradiction only because it rests on a paradox, that time had or was started.
There might be more logical, less trivial ways to state and inquire about the paradox, granted.