Can dark matter be composed, even partly, of black holes?

Context

A recent hypothesis says that dark matter comprises a large number of compact objects such as primordial black holes.

About

Dark Matter Vs Dark Energy:

Dark matter works like an attractive force, a kind of cosmic cement that holds our universe together.
- This is because dark matter does interact with gravity, but it doesn’t reflect, absorb, or emit light.
- Meanwhile, dark energy is a repulsive force, a sort of anti-gravity that drives the universe’s ever-accelerating expansion.
Dark energy is the far more dominant force of the two, accounting for roughly 68 percent of the universe’s total mass and energy.
- Dark matter makes up 27 percent. And the rest, a measly 5 percent is all the regular matter we see and interact with every day.
In short, dark matter slows down the expansion of the universe, while dark energy speeds it up.

What is the recent proposition?

When the universe was very young, hot and dense – soon after the Big Bang, it must have had quantum fluctuations of its density.
This, in turn, would have caused some regions to become extremely dense, and therefore, to collapse under their own gravity to form the primordial black holes.
While we have no conclusive evidence of spotting these objects, some of the binary black hole mergers detected by the LIGO gravitational wave detectors might be primordial black holes.
The question is open there is good reason to believe that primordial black holes did form in the young universe.

Observing dark matter: Gravitational Lensing

The paper explores what happens when such objects get in the way of gravitational waves traveling towards the Earth from the distance.
It invokes a phenomenon called gravitational lensing that is used regularly in astronomy.

What Is Gravitational Lensing?

When taken to the extreme, gravity can create some intriguing visual effects that Hubble’s is well suited to observing.
Einstein’s general theory of relativity describes how mass concentrations distort the space around them.
A gravitational lens can occur when a huge amount of matter, like a cluster of galaxies, creates a gravitational field that distorts and magnifies the light from distant galaxies that are behind it but in the same line of sight.
The effect is like looking through a giant magnifying glass.
It allows researchers to study the details of early galaxies too far away to be seen with current technology and telescopes.