Stucco might not have been mixed well. Bright white is really hard to look at inside a house, even worse where sun is. That said, If you paint you will be redoing it fairly often so better to recoat with well mixed stucco & wear sunglasses to protect your eyes when out there! If you paint better make sure it can handle the chemicals in the pool evaporating. Baptisteries have problems that way & also with fabrics for drapes, wrong fabric & it nearly dissolves in few months. Not as bad outside but don't want to have to redo everything all the time. Good Luck!