There has been a vast growth in plane conversions from passenger to freighter aircraft (P2F) because of falling passenger numbers due to Covid-19.
Before the crisis InsightIQ recorded approx 78,000 freighter flights per month. By December 2020 this had increased to 138,000 as the cargo fleet, including conversions, took cargo which could not be accomodated on other transport media.
Volume shortages inevitably mean higher freight rates, as has happened in the current ocean shipping container market. Judging by the number of aircraft conversion facilities emerging around the world it looks as if the new face of air freight will continue for a while.