Damage on the half. How? Your guess is as good as anyone's. Edge lettering probably has to do with wear from tumbling around.
The first photo I saw, without scrolling down, I thought you found a half with missing clad, but then realized all of your photos of that coin made it look that way. LOL
I'm old. My eyes are old. You're older. You're eyes are older. You're infinitely more experienced and knowledgeable than I ever will be on this topic. I'm going with the @Fred Weinberg attribution of deep scratch. Thanks for weighing in.
Now you know what age, experience and knowledge will do for your standing in the world Don't worry, be happy. I did give your post a 'Like' though.