Philodendron Birkins feature glossy leaves which develop their streaky white variegation as the plant (and leaves) grow. As these plants are very young, they are only now starting to develop some of their streaks. As they grow, their leaves will darken and more vareigation will develop.
Water: Allow the top 1-2 inches of soil to dry in between waterings. Never allow plant to sit in standing water as this may lead to rot.
Light: Loves bright, indirect sunlight. Too little light will lead to loss of colour and variegation. Too much direct light will cause burn.
Soil: Use an airy, well draining potting soil. One containing bark, peat, sphagnum moss, and perlite is ideal.
Humidity: These plants are suckers for humidity. Use a pebble tray or humidifier, and mist often to keep this guy happy.
Fertilizer: Fertilize once a month using a water soluble houseplant fertilizer. Do not fertilize over winter months.