Hello out there!
My parents have a 2010 Hyundai Sonata. About a month ago my mom noticed that when she starts to brake, the car stops fine but then it stops again almost, with a loud thunk. The best way to describe it is that you press down the brake, the car stops, then a few seconds later the car feels like it is lunging forward and stopping again with a sudden thump. (Although I don’t think it really actually moves at all).