Several tall poles with spiral "hook" in a park
The poles (about 5-6 of them) were spread around the park, not in any pattern, not along paths and not on any type of playing field. Too tall to reach the hook (at least 3m tall).
A friend who lives nearby says he has never seen any plants in pots or similar things hanging from them, since that was my initial guess.
Found in this park: https://maps.app.goo.gl/UT3Tp3gG5bRpRuWr8
What is this tall green plastic box just installed by the city?
So this has something to do with water I believe. They were laying down orange pipe along with them. There are multiple at different spots on the waterline path. They each seem to be right next to the valve that our apartment uses to turn water on and off to the buildings.