To add at least one on-topic comment here:

the team achieved 51.3Tb/s transmission over a single 206.5-km unrepeatered span using only erbium-doped fiber amplifier (EDFA) amplification

This is impressive! Our usual spans go to maybe 120 km at most if I use our strongest EDFAs. With those we can deal with around 30 dB of span loss, and most fibers we can rent have around 0.25 dB/km loss. Of course this is on classical single core fiber, we don't use HCF yet.

I remember YOFC was also at last year's ECOC, where they presented their support tube hollow core fiber concept, reaching 0.05 dB/km at some wavelengths. Here's some slides I photographed.