Looks like somebody did a patch job there.
You can get the newer vinyl bang plate from Grady. It's not cheap but under $100. You need to cut it into 3 pieces to make the corner junctions. They told me to seal it with 5200. I did that when I recently repowered. My transom was as dry as a bone.
You need to gets your transom checked out before just replacing the bang plate. It looks scary.