What paradoxical conclusion arises from finding dead, massive galaxies only a few billion years after the Big Bang?

Answer

That these structures "lived fast and died young"

The discovery implies that some of the universe’s largest structures managed to complete their entire life cycle—growth, fuel consumption, and shutdown—at an astonishing speed very early on.

What paradoxical conclusion arises from finding dead, massive galaxies only a few billion years after the Big Bang?
Spacegalaxiesastronomydead galaxies