Looks like the finish dried too quickly. Hazing occurred because the finish drew whatever water/moisture it could in the finish. Nothing can be done with it now.

Was it a hot day when the plaster was applied?

Was the pool filled via water trucks or a garden hose?

We always fill our pool with a water truck as water is part of the curing process. In between loads the surface is continually wet down until the surface is covered with water.

My plaster contractor on a bright, sunny hot day, will tent the pool to shade it and also his crew. It will remain in place until the pool is filled.