not sizing up

hello plant community! 👋

i have a question regarding my philodendron florida beauty. i’ve had this plant for about 6 months now. it has really nice variegation and it gives me new leaves all the time. i have noticed that the new growth is not getting bigger if anything it’s getting smaller which is surprising because otherwise it’s doing really well. i have it in my windowsill and it has 2 sansi grow lights pointed towards it. could the issue be that it’s winter? i’d love some friendly advice 💚