It's hard to see in the picture. To me it looks like there is a crack on the 1st wood laminate nearest the glass, but it's not cracked all the way through.
If it is cracked and if it was mine I'd fill it with some of the runny kind of superglue. I think that surely would make me feel better, I'm not sure how much actual help it would be.
Two of the bows I've made have failed where the shelf is cut. There seems to be much stress there and vibration of the shot doesn't help. In my dealings with this they have usually eventually failed, even with the superglue. The small crack usually became bigger and bigger with more shooting.
But, if it's not really cracked (or not a new crack) and the blemish is original to the bow when new, I'd guess that it would work fine. I'd ask whomever I bought the bow from if it was like this when they got it.
Not sure if this helps.
Aaron