Every other day, Astronomers find things that don't fit their preconceived ideas. They know the answer to the question, so they have to fudge the solution. They do that and expect we don't notice the cheating.
The problem is that to keep their current framework, they have to contort their minds into believing anything. The current cosmological model doesn't allow for an epoch varying G (Gravitational Constant). The reason for it is that there isn't any model for calculating G - G is a Cosmological Constant - like the charge of the electron, etc. Higgs Boson didn't provide a value for G, so life goes on.
My theory provides a formula to calculate G as a function of epoch. In my theory G is stronger when the Universe was younger, so I can easily explain precocious Black-Holes, way too young galaxies, way too far Stellar candles...:)
What can I say... Pretty soon, they will come up with some stupid idea
Here, they conjure up seeds for Black-Hole formation or use another dubious construct (Dark Matter) to explain away the issue. It is an ugly scene...:)