It can be done by the author (self-label), by an app, or by third parties (moderators/curators), depending on the trust model.
Other clients can decide to use that classification/label
--
For moderation purposes. If the behavior is closer to abuse (spam, scams, harassment...), use NIP-56 (Reporting). Reporting harmful/should-be-moderated content.
Original Author posts a kind:1 note with a question
A bot sends a kind:1985 note (NIP-32 https://github.com/nostr-protocol/nips/blob/master/32.md) that labels the content.
It can be done by the author (self-label), by an app, or by third parties (moderators/curators), depending on the trust model.
Other clients can decide to use that classification/label
--
For moderation purposes. If the behavior is closer to abuse (spam, scams, harassment...), use NIP-56 (Reporting). Reporting harmful/should-be-moderated content.