Overall freight rail traffic for September 2020 was down 9.7%, but intermodal (shipping container) rail traffic was actually up 7.1% year over year.
Overall freight rail traffic is now quite close to where it was at the start of 2020, before the pandemic hit.
Freight rail has seen steady long run declines due to a significantly decreasing use of coal to generate electricity, since coal is one of the main things that is transported via freight rail. Coal accounts for 30.1% of originated tonnage for U.S railroads, far more than any other commodity, and its share of overall electrical generation is plummeting.
I think it is fair to conclude that the pandemic effects on freight rail traffic have pretty much completely ended.