Wait, was his Facebook actually private or did he have coworkers added?

Honestly, just focus on listening more than talking for the first few weeks. Tbh your main job is to figure out what your team actually needs from you to do their work better. Schedule quick one on one chats with everyone to hear their side of things. Ngl you will mess up some feedback early on, but own it and keep it simple.

My last time speaking up about that, I got put in charge of the safety committee.