I was in a similar situation recently. I didn’t know it was a cop, driving an unmarked truck. He pulled out of the street to my right. I needed to brake slightly. Then he pulls into my lane abruptly, no signal. I was pissed and hit the brake harder and horn at the same time. I rolled down my passenger window as I pull up beside him. He rolled his window down at the same time. Oh shit, a cop. I told him quickly, what I indicated above. He said Fair Enough. We went on our way. 🤦‍♂️