It's not just the Baratak this is happening with. Every single one of these civilizations has a -1 or -2 being caused by my diplomats. I don't think it's as a result of some faction trait/ability my civ has, because I was using this same civ in my last game and they were green positive effects.
The only difference is this game was started after the recent update/DLC (which I own), and the last one wasn't. Is this a new bug (if it's a bug), or did it exist before?