It is quite plausible for them to be monitoring conversations where this hot new thing that they have just rolled out is participating. Especially when the tech behind has this exact kind of stuff as a known failure mode (see also: any other LLM ever deployed in any public role anywhere hallucinating).

Your phrase "engineers actively monitoring private conversations" has some quantifiers that need examining.

Is every conversation monitored? Nope.

Is every engineer sitting around monitoring conversations all day? Nope.

Could an engineer catch wind of a report with negative impact on their project and hastily try to cover up their mistake? Yeah, buddy. And you know who is real quick to mash that "report" button? Facebook moms.

Yeah, no, I can make all sorts of shit up. I make a habit of it. Until recently, the ability to produce plausible-sounding bullshit was considered an honest signal of intelligence.

The specific point of incredulity was what I took issue with.