Hello 👋 This is Philly, my red philodendron. I've never really understood him but somehow he's nearly 3 and still alive. The bad news... in the last year he's lost all of his largest (bottom) leaves and about to lose another (see photo). I'd really like to understand why! Is the pot now too small? Sunlight? Confusingly, he's still growing new leaves although they're smaller and always higher up. For context, he was ok in my old flat but this has happened since we moved to a 4th floor flat with an east window. Thank you in advance