Too much sun or a feeding gap

What's happening

New leaves bleaching to a pale, washed-out yellow on the window side points to too much direct sun scorching tender growth, which Aglaonema is not built for. Pale, weak new leaves with no recent feeding instead point to a nutrient shortfall, since young growth shows a lack of food first.

How to fix it

Move the plant out of any direct sun into the bright-to-medium indirect light it prefers. If feeding is overdue, start a balanced liquid fertilizer at half strength through the growing season. New leaves that emerge after the change should come in a healthy green and with the plant's normal coloring.

This is general guidance based on common symptoms; individual plants vary.