YouTube Friends are people with whom you can message videos and chat privately on the YT app. When you share a video on YT or receive a message from a YT friend, a private conversation is created where you can view and discuss the video. More info here: https://goo.gl/hFhLcM
That's odd. Could you file a feedback report with these steps: https://goo.gl/1ckkO5 ? While every individual report may not get a direct response, we do review everything and use the details to investigate and fix issues.