see Text "It was an old idea of Stephen Hawking’s: Unseen “primordial” black holes might be the hidden dark matter. It fell out of favor for decades, but a new series of studies has shown how the theory can work. "
Now: "Physicists Argue That Black Holes From the Big Bang Could Be the Dark Matter " Quata magazine : https://www.quantamagazine.org/black-holes-from-the-big-bang-could-be-the-dark-matter-20200923/?fbclid=IwAR18QI1anduvXeCV4ostAKA3ynYky_bMI1sV5hf4iSX0_ehJZkxLU46rSRc
see also: The Electric Universe by Electric Dark Matter Big Bang Black Holes of Quantum FFF Theory. https://vixra.org/abs/1902.0349
The pieces of primary exploded string knot based Big Bang Black Holes are still there as dual Herbig Haro BHs and growing by mergers and lensing spots around galaxies..
The string big bang could be the result of a former Big Crunch Bh. of a cyclic (multi) universe. see below.