My fence this morning looked like this. Can deer hit the fence that hard? Horses don’t have a mark on them. No one was in the paddock I was standing in, so there would be no reason to fight over the fence. I could see that happening if a horse kicked it. The gate (opening on left) was closed.
The board is a good 6ft back where I was standing.
Maybe the deer didn’t see the board and ran straight into it?