Why do the blades lift off the windshield at high speeds?

If your blade is not aerodynamically designed , the air pressure around the blade will cause it to lift, right off the windshield, like an airplane wing. So when you choose a wiper blade shall consider its aerodynamic spoiler.

All of  BAOYI wiper blade with aerodynamic design, it prevents wiper blades lift off the windshield at high speeds very well!