Wow, that's seems to be missing tons of context.
It says it's comparing one week in April 2019 to one in April 2023. That may or may not be cherry picked. No way to tell.
There's also no information about what "activity" is. Number of phone calls? Minutes? Data used? Minutes of activity on each cell phone?
Finally the headline says something about downtown San Francisco, does that imply the entire cities or just referring to downtowns? I would have guessed inside city limits, but that's hard to tell.
So not sure what it's suppose to suggest about what's going on.