The year is 2080, we solved the climate crisis, we solved the poverty crisis. You live in a pretty chill solarpunk utopia that is considerate, sustainably, just and generally safe. The few dangerous places out there are clearly labelled.
Choose one of those signs and explain why it is displayed where it is.
EDIT: for some reasons up/downvotes do not work for me here. Is anyone having similar problems?
Infohazards and cognitohazards, while they exist, we don't know about them enough to discern the amount of harm they cause whether directly or indirectly.
https://scp-wiki.wikidot.com/scp-2521
There is a certain basilik that also comes to mind but I don't want to be responsible for giving you a direct link :-)
While identifying them explicitly is dangerous, they can be detected by the negative. We can also determine something about their effects, if we are careful. Unfortunately it's akin to identifying a minefield by poking it.