Oh lackaday! Woe! Lamentations!
This has just happened.
It's the insert which I had to fit after knocking the wrong corner of the chop off. Unsurprisingly I suppose, it's the top edge of long grain and taking all the force of clamping boards on the edges.
However, what to do about it. I've got some oak, mahogany or ash to go in there, but it will be long grain again but bigger, or I can go pine again. Or... say nuts to it and fit a whole new face to the vice with the grain running vertically. Then I lose the massive flat clamping surface.
Or a short length of vertical grain inset into the chop.