It is just a guess, but I think your private room conversation is more likely to be broadcast in meeting place if you room from there.
The bug would be that it didn't totally disconnect the people who met there before rooming.
Being just a random room broadcast seems to unprobable to me without a reason.
I'd be ready to make some tests.
It only needs three of us in the meeting place to start. 2 go in room and just talk some crap a few minutes. Then… we join all 3 again and see what the result was.
…So if anyone is interested to test it, just hit me on chat.