The first
The Porsche 911 Turbo (964, 1991) had a rear wing that deployed at speed — among the first production cars with electronically-actuated active aero. Earlier examples (the Citroën SM headlights, various 1970s spoilers) were either passive or mechanical.
The American moment
The 2017 Ford GT was a watershed for active aero in American cars — adjustable rear wing for downforce, drag reduction at top speed, and air-brake function. It set lap times that proved aero was now a tunable variable.
The mainstream
By 2020, active grille shutters, adjustable rear spoilers, and underfloor flaps were on plenty of mainstream cars including Camry hybrids and Tesla Model S. Most drivers will never know it's happening.
The point
Aerodynamics used to be a static design choice — pick a shape, live with the drag and downforce numbers. Active aero turns it into a real-time variable. The Ford GT and McLaren P1 made the technology iconic; the Camry made it boring. That's how you know it has won.