I don't know how it was in SF but here in Toronto it got pretty bad and even now large tracts of downtown are devoid, Toronto has an underground pathway system (sort of like a mini-city) that connects a large part of the downtown core its designed so people can get from one building to another without ever going outside in the winter - as you can imagine it got pretty eviscerated during the pandemic. Even now, tons of new condos are going up in the city but the units at the street level (for commercial usage) remain empty even as tenants move in.