How do I report a message or a conversation?

Open the chat's details (tap the name at the top) and tap Report. You can block the person at the same time.

Private chats aren't checked or read by moderators, so a report is how you tell us something is wrong. Message requests have a Report option too.

On a computer you can also report a conversation from its details page: open the chat, click the person's name at the top, then Report.