What happens when 3 phase AC motor running clockwise is suddenly reversed?
There would be arcing at the contactor contacts, due to 'inductive kickback', every time an induction motor is switched off.
When a running motor is reversed, there would be a finite time between the motor switching off in the forward direction, suddenly stopping and then starting in the reverse direction. Hence the same arcing would result.
Such a reversal is called plugging and is one of the methods used to brake an induction motor (power is switched off before it reverses). The resulting high I²R dissipation in the rotor would overheat the motor and necessitate sufficient cooling time between braking cycles.