Malls barely exist, at least compared to the way they did 20 years ago. I wasn't arguing all third spaces are gone, but even of the ones you did note I'd bet in most communities their funding/availability has decreased in that time period.

Malls have been in decline for decades. Public pools barely exist anymore either. (https://www.poolmagazine.com/pool-news/america-is-losing-pub...). If you're in a wealthy city you probably still have a decent community center. Libraries are probably the most common space avilable, but they are also under constant attack by republicans. In wealthy cities you can find all kinds of services there. Smaller libraries will have some areas for reading and meeting.

Malls are dying. Many are closed. Public libraries are daycare for the homeless and parents are afraid to leave their children. Your other options may be well-run, but all suffer from a lack of funding and staffing. Pools aren't a year-round thing, even in the South.