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