My observation. The 60 solar mass star that created the black hole according to stellar evolution, has a very short lifetime, perhaps 5 million years or less so Cygnus X-1 is a very young black hole too. The phys.org report makes this clear, "The black hole in the Cygnus X-1 system began life as a star approximately 60 times the mass of the Sun and collapsed tens of thousands of years ago," he said.",
https://phys.org/news/2021-02-black-hole-massive-thought.html
Compared to ages for primordial black holes or SMBH, Cygnus X-1 black hole is very young
The link at phys.org has 'Cygnus X-1 contains a 21–solar mass black hole—Implications for massive star winds',
https://science.sciencemag.org/content/early/2021/02/17/science.abb3363, 18-Feb-2021. My observation. As space.com reported, the parallax method used to determine distance and size for the new metrics. A 21.2 solar mass black hole, Schwarzschild radius = 6.2609E+01 km or close to 63 km.