This is Destination Direct Inject. The packages are pup'd and move through the Express network until the destination market. In most markets there are multiple FXG locations, but there seems to usually be a hub that can sort the volume.
In general the further out zip codes and rural areas go to FXG. Then more are added and it gets closer to the core of the market. There are separate URSA codes for the ground locations. This has been going on in 5 markets for a little while and the geniuses finally realized the need to add FXE station identifiers on the packages also because... if the ramp sort is late or otherwise does not make cutoff for FXG, then the FXE station must deliver. This is comical because the staffing is reduced based on reduced volume. Not sure how many markets are included now. I'd guess it's eventually coming everywhere.
The tech should be complete around 2023 to scan the package at consolidated buildings to determine if FXGcan make commit or if it must be delivered by FXE to make service.