On the side of the alley within the USBID the streets would be cleaned of litter, poop would be washed, and private security (off duty SFPD hired by the USBID) would monitor the neighborhood.
On the side of the alley that wasn't within the USBID, trash would be dropped, you would see open PCP and Meth use, and poop on the street, and cops wouldn't respond unless a weapon was drawn.
The distance between the two was 5-7 feet. The area within the USBID didn't change drastically compared to pre-pandemic, but the area outside the USBID basically collapsed.
There are a lot of these invisible borders across San Francisco which townies and unhoused people can recognize.