If it’s putting out new leaves it’s using fertilizer to grow. It doesn’t matter what time of year it is. If it’s indoors, seasons don’t really matter except for light levels. When to fertilize also depends on the type of fertilizer and the needs of the plant. In general it’s best to use slow release fertilizer (less chance of over doing it). The best time for that is the spring but 2 doses might be needed. If using liquid, a 1/4-1/8th dose amount with every watering is better.

Monsteras are very dramatic when they run out of nitrogen. They turn a bottom leave bright yellow in a day or two. If you catch it early enough and give them some fertilizer you can save th leaf.

As for light, 3-4 hours in the spring or fall. In nature monsteras are tree climbers. In low light conditions they grow toward the darker patches hoping to find a tree trunk. Then they climb up until they get enough light then produce giant leaves and fruit.