Did you get an ABS fault light on the dash?

Two possible different scenarios.

1/ (likely) you experienced ABS moderating the braking force. The ABS will prevent you from locking the wheels. If you have turned sharp enough while braking it's possible that the wheels may have started to lock. The ABS will send a vibration through the pedal as it limits brake fluid pressure.

2/ (unlikely) your wheel bearings are rooted and when you turn sharpy the movement in the bearing allows the disc to push the pads and fluid back into the caliper and reservior. When you next step on the brake pedal it goes lower to the floor.

When you say it 'cut off braking' did you have a high & hard pedal or a pedal that went to the floor?

Edit; why are you making all these 'abrupt U turns'? I've made maybe 3 in my whole life (on public roads) Are you delivering pizzas? a hopeless navigator? or evading police? all of the above? lol.