Look how the green of this siya? leaf hangs on between its ribs, even though they have largely shut down themselves. It’s like it’s living on its own. A leaf like this won’t be feeding the bush anymore. It’s simply being a leaf.
There’s a similar pattern in the one below. Again, the stem is shot for anything much more than a support.
And here’s one, where the last photosynthesis is huddling around the stem, suggesting that those stems are being drawn down by the leaf.
Rather than the bush draining the leaf to prepare for winter, could it be that the leaf is drawing down the stem, living its independent life? Could all leaves be just this independent? Not “parts” of a plant, but the plant itself, surrounding its support structure. Here, it’s very much like a salmon hanging around its nest for a few days (in this case, that plump purple bud with its new leaves and flowers, folded inside) before letting go?