You can see a goldfish peeking out from that small clear area near the middle. I also took a closeup, but thought it would be more interesting to see the whole pond. It seemed ok to me.
It doesn't appear to be debris considering the plant life is teeming and is still green and does not have appeared to withered or start to decompose. If it was dying and a paler colour, I would agree with you and your statement is correct. I just dispute that the plants in there are counted as debris.