Philodendron 'Birkin', and some others with fancy leaf patterns, have a very narrow threshold for acceptable sunlight. Too little and they lose their leaf patterns; too bright and the leaves become bleached.  The remedy for this problem is simple! It will need some bright but indirect light, so in the New York area allow it space in a south-facing window with a shear curtain or 4 to 5 feet away from that window. East-facing light at a distance of a foot or two is also good. West-facing light will probably scorch the leaves. It will need to be pushed even further away from the light in winter.

Philodendrons are also known to have variations in leaf patterns on a single plant and sometimes become more or less pronounced in coloration as they mature but I hope that's not the case here. 

Courtesy of NYBG Plant Information Service