I did a test in the app, and it is pretty obvious you are posting the chat. You click share, then you are given a preview, and you have to hit post to actually post it publicly.
Then should publishing always be disallowed on all platforms? I’m having trouble understanding how is what Facebook is doing any different from ChatGPT, and in general all web apps.
If you don't communicate at a level suitable for your audience, then you're not communicating. At best, you're just making noise. At worst, you're being a manipulative sack of shit. I do not believe Meta are in the noise-making business.