The app has an “@AI” user which needs to be mentioned for the data to be shared. Chef’s kiss emoji from me in terms of transparency. Also, if you DM @AI it calls out that the message will be shared with OpenAI and Wavelength.
Imagine a group chat on Signal, but in the middle of the chat dangles a big carrot enticing other group members to forward the discussion to OpenAI conveniently.
Sure, there's various other ways someone you talk to could do this silently. But ignorance is bliss vs. an inline feature to flaunt it.