I don't have access to Outlook 2016 to investigate this issue fully. I have MS 365 Business Standard.
NikolinoDEI don't use any plugins normally, I did have a jira plugin installed which I don't use now, so I have removed that. Outside of the Ripcord chat app, the only other reference I came across was a Microsoft dev blog called 'Microspeak: Ripcord' ...