My hunch is that this "dead zone" was detected by productivity tools that noticed email and Teams messages slow down during that time period. I say this becaus

My hunch is that this "dead zone" was detected by productivity tools that noticed email and Teams messages slow down during that time period. I say this because it is relatively well known around my team that 3-6 or so are "working hours" in that, we are all getting stuff done and not chatting.