Buick Transmission problem?

my daughter’s friend has a 1990 Buick Lasabre, 6 cyl automatic- She claims that while driving, if she slows down and brakes to a stop normally, the car will not move when she steps on the gas- the engine will just rev-

If she hits the brakes hard while stopping, the car will move normally when she steps on the gas-

These are the only details given to me thus far but does this make any sense to anyone? Is there any scenario where this might occur?

This sounds just like low fluid level. Park the vehicle on level ground with the engine hot and idling in park and check the fluid level.