My anecdotal impression is that people don't really use those that are available very much and the drop in investment is because of that.
I have organized a few events in community halls over the past few years and I have been struck by just how available the event spaces we looked at were. No conflicts, no competing priorities, nobody using any of the other rooms at the same time, etc. Some communities are no longer bothering to have community halls at all, as nobody really uses them.
Where I live, the local community centres are not heavily used. Community social events have dwindled due to being poorly attended. The coffee shops, bars, and pubs have cut seating and replaced it with dedicated pickup areas for those who send in orders or are buying it through a delivery app. Schools have cut all manner of parent activities as the parents don't participate.
Same thing for anything that isn't a flagship park or flagship sports facility. Sure, the top city parks are crowded, but most are pretty empty even on sunny days.
So I have to ask, is there actually much demand for more social interaction? As it seems that the drop is mostly in demand, not supply.