If water pools up at all they will mud it up. Sometimes not too bad and it can recover but often times if left at it they can do maximum damage in a short timeframe, they're very destruction efficient. They even mud up around their pool if any gets splashed out.
I made the mistake as a new duck owner of letting them out on a rainy day.... and our back lawn has areas the water pools so they practically built a trench.... 🤦♀️
If they free range during mud season in the spring or when it rains in the summer they absolutely can, especially if there's an area where the water may pool a little. Mine did. My back yard has hardly any grass on the flat area and before they decimated the grass they made a mini golf course...