An even better question is why would BH creation remain static?

Let there be no mistake, the who is me.

Dark Matter is likely to be a combination of primordial matter AND the product of annihilation physics during inflation.
Owing to the observations of supermassive black holes very early in the universe, there is speculation they were formed by an abundance of dark matter since there wasn't enough time for baryonic stars to collapse and merge to super massive status. Many think the properties of dark matter black holes are different than BHs today such as having lower temperatures.

Now, regarding black holes and dark energy;
I have held for over a decade that there are far more BHs than the largest estimates ever made. This is being born out by many recent findings. The BHs that broadcast their existence like quasars, pulsars, GRbursters, Super Nova creations, collisions, galaxy centers, rogue, etc. that are visible with radio and optics, are actually the minority of the true number of BHs. In advance of the james Webb findings I will assert their are hundreds of supernovas from stars over 23 solar masses every night in our sky.

Our early estimations were wrong.
So there are far more BHs to begin with but I speak of an accelerated rate.

I found a question regarding a 'strange correlation' and a 'point' in time when the universe just began its current acceleration.
Finding the point of acceleration is done by using red shift values on one end and 'pictures of the early universe on the other end.
The first shift in expansion began when the universe was between 5 and 6 billion years old.

The mass of all the black holes when the universe was 5.5 billion years old was a turning point. This where a leap of thought is required similar to string theory. We know energy can not be created or destroyed. It goes someplace. Inside each Black Hole is a singularity where our laws break down. now hold on.

Black Holes are said to evaporate over time, says Hawking. I defer.
A Black Hole can grow in mass and volume, it can send energy out AND it can send energy in.

Where could it go. It could transform into space energy, which is HIGHLY energetic. A black hole can be a forge here energy and mass can be transformed into its counterpart, space.

From here you should be able to see the rest of my thinking.
This is about the 5th time I have explained my postulate here.
I reject all early verdicts. All that is changed is my improved ability to put forth this theory in lay terms.

If you ask what is the exact rate of increased BH formation you have missed the point. But it will correlate to the rate of acceleration of space. The point is simply describing the source of dark energy, the greatest enigma of our time.