Mushroom island trees

I was testing out seeds and found a mushroom island. But then I noticed something was wrong. All of the mushroom trees (big mushrooms, whatever you want to call them) in the mushroom island were all brown. Like literally, no red polka-dot trees from what I explored, which was the whole biome. I'm really not sure whether this is a bug or a very very very rare coincidence, but it's sorta exaggerated. BTW, I did search to see whether this is a duplicate. Seed: 181181. Co-ords: X: -1246 Z: -784.