Hit debris and my my fuel economy is in the toilet.

So I just got a 2026 with the 3.0 duramax last week. I’ve been regularly averaging high 20s mpg on the way to and from work. Yesterday there was an empty box of DEF in the middle of the highway I couldn’t avoid due to traffic and so I straddled it hoping for the best. In my rear view mirror I thought I saw something resembling a skid plate fly out from under my truck but once I got home I didn’t see anything amiss. But on my way home and since my notables. No goes or alerts, any ideas?