It's come up more often recently because it makes for another interesting competitive aspect to LEO satellite internet systems like Starlink. Once they get inter-sat links working, the higher speed of light from paths through air/vacuum would actually give them lower latency over long distances (sufficient to make up for the extra round trip to orbit). It's also the reason high speed traders in some places have gone to the trouble and expense of setting up point-to-point wireless links over long distances; they too can actually beat a regular fiber signal. Photonic band gap fiber is another expensive but interesting tech that might someday be worth it at least for long distance backbones. It's cool we've come far enough to be able to start looking for further improvements like that. For real time international communications, it might make for a real improvement in many applications.

The velocity factor in different types of copper cables is also around 66% and up to 80%, so can be slightly faster than fiber. Not that it matters much on those distances.

Hence the usage of hollow (air) core fiber to squeeze those extra nanoseconds

This is technical, but the speed of light is constant. This is important to point out because people often get confused with different wave propagation speeds.